Force-feedback interface device for the hand

ABSTRACT

A man-machine interface is disclosed which provides force information to sensing body parts. The interface is comprised of a force-generating device ( 106 ) that produces a force which is transmitted to a force-applying device ( 102 ) via force-transmitting means ( 104 ). The force-applying device applies the generated force to a sensing body part. A force sensor associated with the force-applying device and located in the force applicator ( 126 ) measures the actual force applied to the sensing body part, while angle sensors ( 136 ) measure the angles of relevant joint body parts. A force-control unit ( 108 ) uses the joint body part position information to determine a desired force value to be applied to the sensing body part. The force-control unit combines the joint body part position information with the force sensor information to calculate the force command which is sent to the force-generating device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of Ser. No. 09/076,617 filed May 12,1998 now U.S. Pat. No. 6,042,555 which claims benefit of U.S.Provisional Application Ser. Nos. 60/046,185, filed May 12, 1997, and60/054,654, filed Aug. 4, 1997.

TECHNICAL FIELD

This invention relates to a man-machine interface and in particular toan interface that measures body part positions and provides feedback toa user's hand and arm.

INTRODUCTION Background

A new manner of computer interaction is now in its infancy. The words“virtual environment” or “virtual reality” will soon be commonplace. Avirtual environment is an environment where some portion of theenvironment is artificially simulated, most often via a computer. Acomputer may create a graphic simulation of an environment, completewith graphic images of chairs, windows, doors, walls, etc., and evenimages of other people. The computer may also simulate environmentalsounds. The generated objects may be viewed on a common two-dimensionaldisplay, such as a computer screen, or, by viewing with specialstereoscopic equipment, the objects may be made to appear threedimensional.

The most natural way for an individual to interact in a virtualenvironment is to directly control a graphical representation ofhimself. For example, if the individual turns his head, the displayscreen at which he is looking is appropriately updated. Also, if theindividual reaches out and closes his hand, the computer generated imageof his hand on the screen reaches out and closes. Such virtualenvironments have been discussed in the literature.

To create the sensation of virtual reality, the computer should be ableto generate and manipulate graphic images of real or imaginary objectsin real time. Although generating a graphic representation of anenvironment may be time consuming and non-trivial to implement, much ofthe theory has been explored and is well-understood by those skilled inthe art of interactive 3-D computer graphics and solid modeling. Theinvention described here pertains to the important related area in whichrelatively little research has been done, i.e., “How may a human userperceive grasping force and from his computer-generated counterpart inthe virtual environment?”

There are many peripheral devices which have been created to allow auser to enter information into the computer. The most notable of theseis the standard QWERTY keyboard. Besides the numerous modifications ofthis “key input” concept, there are many other devices with theirassociated permutations. A partial list of such devices includes mice,joy-sticks, trackballs and Computer-Aided-Design (CAD) tablets. The maindrawback of these computer input devices is that they don't permit humanusers to enter information in a manner which may be the most efficientand natural. For example, in a CAD software program, the human designermay wish to rotate a 3-D graphic representation of a block on a computerscreen to view and modify the hidden side. Using currently availableinput devices, the designer must select the axis or a sequence of axesabout which the object must be rotated to achieve the desiredorientation and view. After the desired axis is selected, the amount ofangular rotation must be determined, usually by the linear motion of amouse or by entering the desired amount of rotation as a decimalquantity via the keyboard. This whole procedure seems very awkward andnon-intuitive when compared to what a person would normally do whenconfronted with a similar task in the “real world,” i.e., he wouldsimply reach out, pick up and rotate the object.

Instrumented gloves which provide finger-position information to thecomputer have been used to manipulate simulated objects in virtualenvironments. Such gloves have also been used in telerobotics to controlhighly dextrous end-effectors to grasp real objects. However, lack offorce feedback to the glove wearer has reduced the effectiveness ofthese open-loop manipulation approaches. Imagine a 3-D graphic model ofan egg on a computer screen. Suppose you are wearing a glove which mapsyour finger and hand motions to a graphic image of a hand on the samescreen as the egg. As you move your hand and fingers, the correspondinggraphic images of the hand and fingers move in a similar manner. Thetask is to move your own hand and fingers to control the graphic hand onthe computer screen to pick up the egg. To accomplish this task you mustprovide enough force to reliably grasp and lift the virtual egg, but notso much force such that the egg is crushed. Without some kind ofgrasping force and tactile feedback, this task would be extremelydifficult.

Attempts have been made to provide information about simulated contactwith virtual or telemanipulated objects to senses other than thecorresponding tactile senses. One method of simulated feedback which hasbeen tested uses audible cues. For example, the computer may beep whencontact is made. Another simple method is to highlight the object oncecontact is made. Both these methods will require the user to re-learnhand-eye coordination. It may be frustrating and time consuming for theuser to learn one of these “unnatural” methods of grasping an object,and the sensation of interacting in a virtual environment will bereduced.

More recently, approaches have been developed to directly exert forcesto the fingertips. One such approach uses pneumatic pistons located inthe palm of the hand to exert resistive forces at the fingertips. Thedisadvantages of such an approach are numerous. First or all, pneumaticcylinders have low mechanical bandwidth and cannot exert very largeforces because the limited workspace of the palm limits their size.Additionally, such actuators tend to be noisy and the fact that they arelocated in the palm limits the range of motion significantly. Otherapproaches have used servo-motors located directly on the back of thehand. Such approaches tend to be quite bulky and often need to besupported by robotic arms and thus are not well suited for desktopapplications. When robotic arms are not used, hand and arm fatigue areoften a problem as it is quite difficult to produce a device that issmall and light enough for prolonged usage. Additionally, such devicesoften do not provide feedback to all the fingers in an effort tominimize bulk. Finally, such devices typically suffer from a limitedrange of motion which hinders manipulation.

Therefore, it will be appreciated that there remains a need for aman-machine interface for the hand that is capable of sensing finger andhand positions and hand orientation, that provides appropriateforce-feedback, and that overcomes the other limitations in thestate-of-the-art as described herein before.

One object of the invention is to provide a man-machine interface whichmay be employed in interactive computer applications. Another object ofthe invention is to provide a force feedback control system capable ofcontrolling a set force to a selected part of the body, e.g., thefingertip. et another object of the invention is to provide aman-machine interface comprising a glove capable of sensing finger andhand positions and hand orientation, which may exert, measure anddynamically vary and control the forces applied to each finger. Anotherobject of the invention is to provide a digital control system capableof sensing the force applied to the fingertip and capable of using thisapplied force signal to control the fingertip force to a desired forceset point which may vary as a function of finger position. Still anotherobject of the invention is to provide a force feedback system which maybe employed in many different applications, such as virtualenvironments, telemanipulation and interactive 3-D graphics,telerobotics and Computer Aided Design (CAD). Yet another object of theinvention is to provide more natural and intuitive feedback duringobject/environment interaction.

SUMMARY OF THE INVENTION

The subject invention introduces new techniques for providing graspforce feedback and grounded force feedback to the hand of a wearer. Thefeedback techniques are largely predicated on transmitting a force froma remotely located actuator to the site of force application via atendon-in-tendon-guide structure. Various tendon/tendon guide structuresare provided, some comprising flexible tendon guides and some comprisingrigid tendon guides. In one useful embodiment of the subject invention,the tendons are routed over a series of moment-augmenting structures onthe dorsal surface of the hand, where the structure determines the levelof moment applied to joints of the hand for a given fingertip force. Thestructure is typically designed such that a larger moment is applied tothe metacarpophalangeal joint than a joint more distal. In anotheruseful embodiment, 5- or 7-bar linkages are used to apply force only tothe fingertip relative to a location typically either on the back of thehand or a structure supported by a ground-referenced robotic arm. Whenused with a ground-reference robotic arm, grasp-force devices becomelightweight, low-inertia ground-referenced force-feedback devices.

In one aspect, the inventive structure provides apparatus for attachmentto a body where the body has a sensing body link connected to anon-sensing body link with at least one sensing body joint between thesensing and non-sensing body links. The apparatus includes means forapplying force to the sensing body link, attachment means for attachingto the means for applying force and to the non-sensing body link, andmeans for generating a force at the sensing body link and a moment atthe sensing body joint. The apparatus also includes means for applyingthe generated force between the sensing body link and the non-sensingbody part. In one embodiment of the inventive structure, the means forapplying the generated force includes a moment-augmenting structure(such as for example, towers and cams). The inventive structure alsoincludes a tendon elevated by the moment-augmenting structure, where thetendon is connected at the force-applying means at one end, and to theforce generating means at the other end; and tendon guiding means forguiding the tendon between the force-applying means and the forcegenerating means.

In one particular embodiment, the moment-augmenting structure comprisesfirst and second elements connected by an articulated link such that thetwo elements move in the same plane. In another embodiment, themoment-augmenting structure comprises a composite member of somecomplexity comprising a flexure-articulating component and anabduction-articulating component, the composite member further comprisestwo revolute joints, wherein the flexure-articulating component isattached to the abduction-articulating component by one of the revolutejoints and rotates relative to the abduction-articulating component, andthe abduction-articulating component is attached to the attachment meansat the non-sensing body link by means of the other one the revolutejoints. In still another embodiment, the moment-augmenting structurecomprises a simple member including means for attachment to anintermediate link between the sensing and non-sensing links and atendon-elevating guide connected to the attachment means.

In another embodiment, the force-applying means includes a platformdisplaced from the sensing body link when in an unactivated position andin contact with the sensing body link when in an activated position. Instill another embodiment, the apparatus may include a second forcegenerating means connected to the apparatus for providing force to theapparatus relative to a reference point off the body.

In one embodiment of the inventive method for use in a device forattachment to a body having a sensing body link connected to anon-sensing body link, includes the steps of: applying force to saidsensing body link; attaching the body to the force-applying means and tosaid non-sensing body link; generating a force at the sensing body linkand a moment at said sensing body joint; and applying the generatedforce between the sensing body link and the non-sensing body part; thestep of applying the generated force comprising applying the force via amoment-augmenting structure and a tendon elevated by themoment-augmenting structure, where the tendon is connected to receivethe generated force at one end and to apply the applied force at theother end; and guiding the tendon between the force-applying means andthe force generating means.

A control system and method that senses the force applied to thefingertip; and controls the fingertip force to a desired force set pointin response to the sensed applied force signal, where the desired forceset point may varying as a function of finger position, is alsodescribed.

In one aspect, the invention provides for the use of a flexible housingwhich may comprise one or more concentric flexible casings which guide aforce-transmitting flexible elongated element such as a flexible, lowfriction/stiction, high modulus of elasticity thread or a shape-memoryalloy wire which serves as a tendon and is used in tension to applyforce to a sensing body part. In another aspect, the invention providesfor the use of force actuators to generate force which is transmitted tothe sensing body part via flexible tendon cables, or pneumatic orhydraulic tubes, and used by a force applicator to apply force to thesensing body part. In still another aspect, the invention provides forthe use of a support to which the flexible tendon cables or tubes aresecured. The support may be a reinforced wrist-strap when the sensingbody part is part of the hand. In yet another aspect, the inventionprovides for the use of a mechanical structure to augment the mechanicalmoment and which is attached to the back of the hand to route forceapplying tendons to each of the fingertips without hindering handmovement and exerting resistive forces at the fingertips as well asresistive torques at the finger joints. In a further aspect, theinvention provides for the use of a pressure, tension and/or forcesensor to measure the force applied to the force-sensing body part bythe force actuator.

Additional objects, features, and advantages of the inventive system,apparatus, and method will be more readily apparent from the followingdetailed description and appended claims when taken in conjunction withthe drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects and features of the invention will be more readilyapparent from the following detailed description and appended claimswhen taken in conjunction with the drawings, in which:

FIG. 1 is a diagrammatic illustration of an exemplary embodiment of asystem employing the force feedback structure mounted atop aninstrumented glove that measures the position of the hand in conjunctionwith the controlling components.

FIG. 2A is a diagrammatic illustration showing a side view of anexemplary embodiment of a force feedback device attached to a referencepoint off the body (ground);

FIG. 2B is a diagrammatic illustration showing a perspective view of anembodiment of the articulated interface that connects the force-feedbackdevice to a reference point off the body (ground); and

FIG. 2C is a diagrammatic illustration showing a side view of anembodiment of the articulated interface that connects the force-feedbackdevice to a reference point off the body (ground).

FIG. 3 is a diagrammatic illustration showing a side view of themechanical structure of a thumb-controlling force-feedback device.

FIG. 4A is a diagrammatic illustration showing a side view of themechanical structure of an index-finger-controlling force-feedbackdevice;

FIG. 4B is a diagrammatic illustration showing a perspective view fromthe top of a whole-hand-force-feedback-device.

FIGS. 5A and 5B are diagrammatic illustrations showing respectively sideviews of the tendon-guiding mechanism in a flexed and extended position;and

FIG. 5C shows a perspective view of a front cam which includes bothrigid and flexible tendon guides.

FIG. 6 is a diagrammatic illustration showing a side view of analternative embodiment of the mechanical structure of anindex-finger-controlling force-feedback device.

FIG. 7A is a diagrammatic illustration showing a side view of anotheralternative embodiment of the mechanical structure of anindex-finger-controlling force-feedback device; and

FIG. 7B shows an end view of an individual tendon guide.

FIGS. 8A-8E are diagrammatic illustration showing several exemplaryembodiments of tendon-tension sensors

FIG. 9 is a diagrammatic illustration showing a side view of analternative embodiment of the mechanical structure of anindex-finger-controlling force-feedback device having a plurality oftendons for individual joint torque control.

FIG. 10A is a diagrammatic illustration showing a side view of analternative embodiment of the mechanical structure of anindex-finger-controlling force-feedback device using a single towerstructure;

FIG. 10B shows a side view of the mechanical structure of anindex-finger-controlling force-feedback device using two towerstructures; and

FIG. 10C shows a perspective view of the mechanical structure of anwhole-hand-finger-controlling force-feedback device using one towerstructure per finger.

FIG. 11A is a diagrammatic illustration showing a side view of anotheralternative embodiment of the mechanical structure of anindex-finger-controlling force-feedback device; and

FIG. 11B shows an end view of an exemplary individual tendon guide.

FIG. 12A is a diagrammatic illustration showing a side view of anotheralternative embodiment of the mechanical structure of anindex-finger-controlling force-feedback device showing towers of varyingheights;

FIG. 12B shows an end view of an individual tendon guide; and

FIG. 12C is a perspective view of the mechanical structure of awhole-hand-controlling force-feedback device showing towers of varyingheights for all five fingers.

FIG. 13A is a diagrammatic illustration showing a side view of anotheralternative embodiment of the mechanical structure of anindex-finger-controlling force-feedback device showing towers of varyingheights; having connecting links; and

FIG. 13B shows an end view of an individual tendon guide;.

FIG. 14A is a diagrammatic illustration showing a side view of anotheralternative embodiment of the mechanical structure of anindex-finger-controlling force-feedback device capable of exertingforces in the finger plane; and

FIG. 14B is a side view of another alternative embodiment of themechanical structure of an index-finger-controlling force-feedbackdevice capable of exerting forces in the finger plane as well as theabduction/adduction plane;

FIG. 15A is a diagrammatic illustration showing a perspective view ofthe embodiment of FIG. 14A;

FIG. 15B is a perspective view of the embodiment of FIG. 14A showingmechanical structures above each finger; and

FIG. 15C a side view of another alternative embodiment of the mechanicalstructure presented in FIG. 15A;

FIG. 16A is a diagrammatic illustration showing a side view of anotheralternative embodiment of the mechanical structure of anindex-finger-controlling force-feedback device capable of exertingforces in the finger plane;

FIG. 16B is a perspective view of the mechanical structure of awhole-hand-controlling force-feedback device using the mechanismpresented in FIG. 16A; and

FIG. 16C is a side view of another alternative embodiment of themechanical structure of an index-finger-controlling force-feedbackdevice capable of exerting forces in the finger plane as well as theabduction/adduction plane;

FIG. 17 is a side view of another alternative embodiment of themechanical structure of an index-finger-controlling force-feedbackdevice capable of exerting forces in the finger plane;

FIG. 18 is a side view of another alternative embodiment of themechanical structure of an index-finger-controlling force-feedbackdevice capable of exerting forces in the finger plane;

FIGS. 19A and 19B are diagrammatic illustrations of a side cross-sectionand a perspective view of an illustrative embodiment of a motor-spoolassembly, which demonstrates how a motor may control tendon position;

FIG. 20 is a block diagram of a canonical motor-control system;

FIGS. 21A and 21B are a longitudinal cross section of a flexible tendonin a useful embodiment of a flexible sheath tendon guide;

FIGS. 22A-22E are diagrammatic illustrations showing various pinnedjoints which may be employed when routing a tendon 2200 from theactuator to its desired final destination;

FIGS. 23A-23D are diagrammatic illustrations of various convenientforce-transmitting means;

FIG. 24 is a diagrammatic illustration of a pinned joint, such asprovided in FIG. 22A, being used to transmit tendon tension to the hand;

FIGS. 25A and 25B are diagrammatic illustrations of useful conversion ofthe movement of a circulating tendon loop;

FIG. 26 is an illustrative embodiment, similar in structure to FIGS. 15Cand 14, but where the pulley-support structure is not supported by thehand;

FIG. 27 is similar in principle to FIG. 26, with the main differencebeing the replacement of the variation on the 5-bar linkage with a 7-barlinkage;

FIG. 28 is a diagrammatic illustration extending the structure of FIG.26 to two hands, and where a force-programmable robot is shown;

FIG. 29 is a diagrammatic illustration showing a force- andposition-programmable robotic arm which may be used as amacro-manipulator, or as a grounded-force device which attaches to thegrasp-force device of FIG. 1, and the like;

FIG. 30 is a diagrammatic illustration of a hand-feedback device, suchas provide by FIG. 1, and the like, being attached at the fingertip to aforce- or position-programmable robot arm by a coupler;

FIG. 31 is a diagrammatic illustration of a fingertip of a hand beingpositioned by a robotic-arm-like device, connected to the force-applyingdevice via a coupler;

FIGS. 32A and 32B are diagrammatic illustrations of a movement-impedingapparatus;

FIGS. 33A-33D are diagrammatic illustrations a canonical force-feedbacksystem, representing any of the force-feedback embodiments described inthe subject application, being used with a 3D display system;

FIG. 34 is a diagrammatic illustration of a simulation chair;

FIG. 35 is a diagrammatic illustration of a variant on the simulationchair of FIG. 34.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Reference will now be made in detail to the specific embodiments of theinvention, which are illustrated with reference to the accompanyingfigures. We begin with an overview of some features of the inventivestructure and method and then describe particular inventive featureswith reference to exemplary embodiments illustrated by the accompanyingfigures.

One embodiment of the invention provides the use of a gloveincorporating not only sensors which provide analog values representingfinger and overall hand motion, but also true force feedback to thewearer's fingertips relating the amount of force a corresponding graphic(or actual) device is applying to a given virtual (or telemanipulated)object.

The invention, which senses one or more body part positions and providesforce feedback to one or more body parts, permits a relatively “natural”method of computer interaction. The subject device provides for: (1)controlling body part position-sensing means employing a plurality ofsignal-producing means associated with individual movable controllingbody parts, where the signal is related to controlling-body-partposition, with the individual signals analyzed to define a compositesignal; where the signal-producing means may be anything which providesbody part position and/or orientation, mechanical, electrical oroptical, including strain gage, electromagnetic, ultrasonic,piezoelectric, Hall effect, infrared emitter/detector pair,encoder/potentiometer, laser scanning or other position and/ororientation sensors; (2) force-applying means which may be anythingwhich provides force information to a sensing body part; (3)force-sensing means which may be anything which provides aforce-measurement signal; (4) force-generating means which may be anyactuator which generates a force (or displacement), includingelectrical, electromagnetic, electromechanical, pneumatic, hydraulic,piezoelectric, shape memory alloy (for example, Nickel/Titanium alloys),vapor pressure actuators, and the like; (5) force-transmitting means(for example, a tendon/sheath assembly, exemplified by a flexible,inelastic tendon guided by a flexible, incompressible housing, or ahydraulic assembly exemplified by an incompressible fluid guided by aninelastic housing), which may be anything which transmits a force signalfrom a force-generating means to an applying means (for example, aforce-applying means); (6) signal-collection and producing means (forexample, a processor or computer) for collecting signals (for example,from the position-sensing and/or force-sensing means) and producingsignals (for example, for the force-applying means); and (7) supportstructure (including clips, straps, clamps, guides, cams, rollers,pockets, material, and the like) used to support the body part sensingmeans, the force-applying means, the force-generating means, theforce-transmitting means and the signal collection and producing meansand attach the various components in their operative organization to thebody part.

The signal associated with the controlling-body-part position-sensingmeans may be coordinated with the force applied to a sensing body. Forexample, the signal produced by the controlling-body-partposition-sensing means may be used by a signal-collection and producingmeans to manipulate a multi-articulated computer-generated interactiveentity in a virtual environment. The force-applying means may applyforce to a sensing body part in relation to the interaction between theinteractive entity and a component of the virtual environment to furtherenhance the sensation of reality.

A particular application for the invention is to sense and provide forcefeedback to the hand. A useful embodiment for the invention when usedfor the hand includes a “feedback glove.” The feedback glove embodimentcomprises means for measuring position and orientation of the hand inspace relative to a given reference, means for measuring individualjoint angles, means for applying force to various parts of the hand anddesirably means for sensing the applied force. Many of the specificdescriptions of the invention will be centered around the feedbackglove, however, the sensing and structures described for the glove maybe translated to other body parts (e.g., arms, legs, feet, head, neck,waist, etc.).

In one embodiment of the feedback glove, the means for providingposition and orientation of the hand in space is a Polhemus™ orAscension™ electromagnetic position sensor. The individualjoint-angle-sensing means comprises two long, flexible strain gagesmounted back to back. The strain gage assemblies reside in guidingpockets sewn over each joint. When a joint is flexed, one of the straingages of the corresponding pair of gages is in tension, while the otherstrain gage is in compression. Each pair of two strain gages comprisethe two legs of a half bridge of a common Wheatstone bridgeconfiguration. An analog multiplexer is used to select which of the halfbridge voltages is to be sampled by an analog-to-digital converter. Themaximum strain experienced by each gage is adjusted by varying thethickness and elastic modulus of the backing to which the gages aremounted. The backing is selected to maximize the signal output withoutsignificantly reducing the fatigue life of a gage. These joint anglestrain gage sensors are disclosed in the Kramer et. al. U.S. Pat. No.5,047,952 and are incorporated herein by reference.

Means for applying force to parts of the hand comprises means (e.g., anelectric motor or a hydraulic actuator) for generating a desired force,means (e.g., a flexible tendon/casing assembly) for transmitting thegenerated force to force-applying means, and means (e.g., aforce-applying platform) for transferring the force to a specific partof the hand (e.g., the fingertip). The feedback glove may also comprisea means (e.g., a force-sensing platform or load cell) for measuring theapplied force. The embodiment includes structure which supports thetendons and casings, usually at least at their ends, and also supportsthe force-applying means.

The force-feedback glove embodies joint angle sensors and theforce-feedback apparatus. The force-feedback glove overcomes many of theproblems of joint sensing devices which do not incorporate forcefeedback. The force feedback glove simulates contact and graspinginformation in a “natural” manner to a user and facilitates many tasks,such as those arising in interactive 3-D graphics and telerobotics. Theforce-feedback glove may be used to feed back force information from“virtual” objects in a virtual environment or from remote “real” objectswhen used in telerobotic applications.

When used with appropriate animation and control software, theforce-feedback glove provides joint-angle sensing and sufficient forcefeedback for a user to control an interactive entity, such as acomputer-generated graphic representation of his/her hand to reliablygrasp a virtual object, such as a cup, or any object which appears as agraphic model on a display device. Some virtual objects are programmedto demonstrate physical properties similar to real objects, such asweight, contour, stiffness and friction. These, and other features, maybe sensed and the virtual objects manipulated using the force-feedbackglove. The force feedback incorporated into the glove relays the virtualgrasping force information to the user when he “touches” virtual objectswith his own computer simulated virtual fingers.

The force-feedback glove, which provides joint angle sensing and forcefeedback, may also be used for telerobotics. For this application, theforce-feedback glove provides joint angle information which is used tocontrol an interactive entity, such as a robot manipulator, to grasp aremote real object. The force feedback of the glove provides the userwith information about the actual grasping forces experienced by therobot's gripper, or robotic hand, such that the real object may be morereliably grasped and manipulated with reduced likelihood of dropping orcrushing.

The glove employing force feedback may also be programmed to teachfinger dexterity, finger timing and even the motions necessary to learnsome musical instruments. For example, if the user were learning thepiano, as fingers are flexed, the user would receive fingertip pressurefrom virtual keys signifying to the user that he had pressed the key.Tendons similar to those positioned on the dorsal side of the fingers torestrict finger flexure may also be placed on the palm side of the hand.These palm-side tendons may be used to force the fingers into thedesired flexed positions or to restrict the fingers from extending.These tendons would be used in the case when the user wanted to be“taught” to play the piano and wanted his fingers to be properlypositioned and flexed for him at the proper times. The idea of thisexample may be extended from a virtual piano to other virtualinstruments and even to other devices such as a virtual keyboard. Thefeedback glove could be used to teach someone to type, and when learned,to allow the user to generate text by “typing in the air.”

More specifically, the invention is a man-machine system which, inaddition to measuring actual human joint angles, provides one or morefeedback sensations to the user. While the subject device finds primaryapplication with a human, the device may be used with other animatevertebrates, such as other primates, where the vertebrate has anappropriate body part. In one embodiment, a small device is attached tothe fingertip of a joint-angle-sensing glove and holds a force-applyingplatform in juxtaposition to the fingertip (see, for example, U.S. Pat.No. 5,631,861, for the described embodiment, as well as alternativeembodiments.) The force-applying platform is displaced from thefingertip (by about 4 mm) by a retractable means (e.g., a leaf spring)when inactivated, but is capable of quickly contacting the fingertip andapplying a dynamically selectable force when activated. The suddenimpact of the force-applying platform provides a sensation similar tothat perceived when the actual fingertip contacts an object. Thereafter,the force-applying platform presses against the fingertip with aprogrammable force which may relate the amount of force that a virtualfinger is pressing against a virtual object.

In another embodiment, the force that is applied by the force-applyingplatform to the fingertip is transmitted from a force-generatingactuator (a DC servo motor) via a high tensile strength, flexible tendonenclosed in a flexible, non-compressible tubular casing. The function ofthis assembly is similar to a bicycle brake cable. Other embodiments mayemploy force actuators based on electrical, electromagnetic,electromechanical, pneumatic, hydraulic, piezoelectric,shape-memory-alloy (e.g., Nickel/Titanium alloys), vapor pressure, orother suitable technologies. In choosing the appropriate actuatortechnology, various factors will be considered, such as speed ofresponse, force output, size, weight, cost and power consumption.

One end of the tendon casing is secured near the force actuator and theother end is secured to a support on the glove itself, such as on thedorsal side of the metacarpus, or to a wristband near the feedbackglove. As a tendon emerges from the end of the casing secured to theforce feedback structure or exoskeleton, it is routed by a guidingmeans, e.g., grooved cams, until the tendon reaches its designated finallocation, for example, the force-applying platform at the fingertip.Tendons which are to provide a force to restrict the wearer from flexinga finger are guided across the dorsal or palmar side of the hand to thefinal location. In addition, a tendon may be terminated at any properlyreinforced intermediate glove location.

As tension is increased, tendons which pass along the mechanicalstructure of the device, exert a force on the mechanical structure,which in turn exerts a force against the underlying finger. This force,in combination with the force at the fingertip, produces a resistivetorque at the finger joints.

To provide a force to restrict the wearer from extending a finger or toactually drive a finger into a flexed position, tendons are guidedacross the palm side of the glove by sections of casing. In oneembodiment, these tendons are guided to the fingertip where they areultimately secured to a force-applying platform, but they may alsoterminate at properly reinforced intermediate positions. Unlike the casewhere the tendons are guided along the back-side of the hand, when thetendons which are guided along the palm-side of the hand are in tension,they tend to pull the casing sections (and hence the glove material)away form the hand. Although not necessary, if it is desired to guidethese tendons along the surface of the palm and fingers as they passfrom where the casings are secured to the wristband to their finaldesignated locations, the glove must be appropriately reinforced betweeneach joint. (See for example, U.S. Pat. No. 5,631,861.) Alternatively,one may provide a mechanical structure which, much like the structure onthe back side of the hand, will guide the tendon away from the palm,thus producing larger torques at the finger joints for the same force atthe fingertip, as compared to the embodiment described in theaforementioned patent.

Where the tendons are routed and where they are ultimately secured tothe glove will determine the forces applied to the hand by the tendon.Forces and torques applied to parts of the hand by a single tendon maynot be controlled independently. Only the force applied to one part ofthe hand or the torque applied by the tendon to an individual joint maybe controlled. In a preferred embodiment, the tendons are fastened tothe force-applying platforms at the fingertips, and the forces at thefingertips are measured and controlled, not the torques applied to thejoints. To isolate the force and independently restrict motion of asingle intermediate joint, a separate tendon is used. Its casing issecured just prior to the joint, and the tendon is fastened to aforce-applying platform just beyond the joint.

In a preferred embodiment, the actual force at the fingertip is sensedand fed back to a servo control system. The control system controls theoutput of the force actuator such that the force applied to thefingertip follows a desired force profile. The force profile for anyfinger is a function which produces a desired-force set point for anygiven finger and hand position. That is, as either the finger or handchanges position, the force applied to the fingers varies accordingly.For example, a force profile may be generated which simulates the forcesensation of a push button switch that gradually increases its opposingforce as the button is depressed until it reaches its toggle point,clicks, and releases most of its resistive force.

The devices provided in the subject application may also be used withvarious other feedback-signal-generating devices, such as air bladdersfor pressure feedback, heat and cold-generating devices,tactile-feedback generating devices, force-applying platforms, and thelike. Such other feedback-signal-generating devices may be used as arefound in Kramer U.S. Pat. Nos. 5,184,319 and 5,631,861, which patentsare incorporated herein by reference. In addition, the force-generatingdevices described herein may conveniently be replaced by brakes,clutches, ratchets, and the like, as appropriate.

Attention is now directed to the specific embodiments illustrated in thefigures. In FIG. 1, there is illustrated an overview of the system andmethod employing the force-feedback device as applied to a hand. Thesystem 100 comprises a force-applying means 102 (indicated by the boxdesignated by broken lines) mounted on a hand wearing an instrumentedglove 136, a force-transmitting means 104, a force-generating means 106,a force-control unit 108 communicating with a host computer 110. Theforce-generating means 106 comprises an actuator 112, conveniently anelectric motor, and desirably a tendon tension sensor 114. The actuator112 may incorporate a position sensor for closed-loop control purposes.The force-transmitting means 104 comprises a tendon casing 116 andtendon 118, shown exposed at both ends of the casing 116. Theforce-applying means 102 comprises a moment augmenting means orstructure 103, such as for example, a mechanical superstructure havingtendon-guiding cams 120 and 122 which route the exposed tendon 124 tothe force applicator 126, located at the fingertip. Various cam contoursmay be selected to provide desirable joint-moment vs. joint-anglemappings. The front and rear cams 120 and 122 are mounted to front andrear supports 128 and 130, respectively, and are attached together byconnecting link 132. The force applicator may contain a force sensor forclosed-loop force or impedance control at the fingertip. The front andrear cam supports 128 and 130 are mounted over the instrumented glove136. The glove 136 has a wrist strap 138 which serves to anchor one endof the tendon casing 116. This strap can also be located on themetacarpus. The force control unit 108 comprises a processing unit,which has the necessary hardware and software to control the actuator112 to which it is operatively connected. The force control unit 108will also detect the signals from the force sensor 134 and the tendontension sensor 114, and the actuator position sensor, if present. Theforce control unit also communicates with a host computer 110, where thecomputer simulation resides or which controls a robot.

By elevating the tendon off the surface of the finger instead of routingit closer to the surface, it is possible to exert larger resistivetorques at the finger joints for an identical tension in the tendon. Themechanism transmits the tendon forces to the force applicator 126 at thefingertip while simultaneously exerting reaction forces to the hand viathe cam supports 128 and 130. These reaction forces produce reactiontorques at the finger joints that prevent the wearer from flexing thefinger. The system is shown with a single force-applying means, but thedevice may include a plurality of force-applying means, such as one foreach finger and/or for one or more joints. These force-applying meansconsist of an individual force-producing means, force-transmitting meansand force-generating means, so that each fingertip and, whenappropriate, each joint can be individually controlled. Theforce-control unit monitors the signals received from the varioussensors to ensure that the forces exerted on the hand conform with thedesired forces.

In FIG. 2a a portion of the system depicted in FIG. 1 is shown inconjunction with a grounding device capable of referencing the handforces to the physical world, as also depicted in U.S. Pat. No.5,631,861, the contents of which are incorporated in their entiretyherein by reference as if explicitly included. The grounding device 200(indicated by the box designated by broken lines) is an articulatedforce-generating apparatus of which there are many possible embodiments.As depicted in FIG. 2, the device comprises articulated linkages 202,204 and 206, with revolute or prismatic joints 208, 210 and 212, whichmay comprise associated actuating and sensing means. Articulatedinterface 214 serves to connect the grounding device 200 to thehand-force-feedback device 216 (indicated by the box designated bybroken lines) at the wristband 218, although it may be attached at othersites, such as the back of the hand or the palm. The articulatedinterface 214 may comprise position sensors capable of measuring theposition and orientation of the hand-force-feedback device 216 relativeto the grounding device 200. Additionally this interface may beactivated to provide up to an additional three degrees of freedom offorce feedback, for a total of six or more. In operation, aforce-control unit, substantially as described above in FIG. 1, willcontrol the force or torques exerted at the individual joints and alsoread all corresponding position sensors, including the ones at thearticulated interface. As the physical hand moves, the grounding device200 can be controlled such that it tracks the hand's movement withoutexerting forces on the hand until such forces are desired by the hostcomputer. When the virtual hand interacts with a virtual object, or arobot interacts with a physical object, the grounding device combinedwith the hand force feedback device will exert corresponding forces onthe arm and hand.

FIG. 2b is a perspective view of a more detailed illustration of theembodiment of the articulated three degree-of-freedom interfacedescribed in FIG. 2a. It consists of two concentric rings 2032 and 2034.The smaller of the two rings 2034 is attached to the larger ring 2032via pivot joints 2036 such that the inner ring 2034 can rotate inside,and with respect to, the outer ring 2032. The pivot joints are equippedwith bearings, bushings or any other suitable means which provideminimal rotational friction. This comprises the first degree-of-freedomof rotation of the interface 2030. It should be noted that for the outerring, a half-ring and even a quarter ring can also be used. If aquarter-ring is used, one of the pivot joints 2036 is not omitted. Theouter ring 2032 is attached to the grounding device described in FIG. 2avia a pivot joint 2038. This comprises the second degree-of-freedom ofrotation of the interface 2030. A variety of materials can be used toproduce stiff yet light rings such as, but not limited to, titanium,graphite, carbon fiber, aluminum, steel and rigid plastics. Inside theinner ring 2034 resides an attachment 2042 which serves to affix theinterface 2030 to the backplate 2046 of the force-feedback means whichis the main subject of this invention. For clarity, the force-feedbackmeans is omitted. The attachment 2042 is connected to the backplate 2046using any convenient means such as a thumb screw, clamp or the like, inorder to facilitate attaching/detaching it from the backplate 2046. Thebackplate is attached to the hand 2040 by any convenient means, such asstraps, belts or the like. The attachment 2042 interfaces with the innerring via a set of three or more wheel-like rotational mechanisms 2044.These rotational mechanisms let the backplate 2046 rotate with respectto the inner ring 2034 and form the third degree-of-freedom of rotationof the interface 2030. It is desirable to add a sensing means to each ofthe degrees-of-freedom in order to determine the orientation of the handin space. These sensing means may include, but are not limited to,encoders, potentiometers, Hall-Effect sensors and the like. Greaterdetails of such an implementation are given in FIG. 2c.

In operation, the articulated interface 2030 acts as a threedegree-of-freedom revolute joint with angular position measuringcapabilities and it transmits forces from the grounding device to theforce-producing means located on the hand. It may be designed such thatthe three major axes of rotation intersect at point located in the palmof the hand or any other suitable location. By having intersectingrotational axes, it is possible to exert a three-dimensional point loadon the hand at the intersecting point. This is of particular concern ifthe articulated interface is not capable of transmitting torques to thehand. Typically, such an interface is used with a grounding device suchas the one described in FIG. 2a which can exert three degrees-of-freedomof force. In another embodiment, it may be desirable to add torqueproducing means to each of the three-degree-of-freedom of thearticulated interface 2030. This may be the case if asix-degree-of-freedom grounding device is used.

FIG. 2c is a side view of the articulated three degree-of-freedominterface described in FIG. 2b which illustrates where angular positionsensing means may be located on the device 2060. It shows the twoconcentric rings 2062 and 2064. The smaller of the two rings 2064 isattached to the larger ring 2062 via pivot joints 2066 at the bottom and2068 at the top, such that the inner ring 2064 can rotate inside, andwith respect to, the outer ring 2062. This comprises the firstdegree-of-freedom of rotation of the interface 2060. The outer ring 2062is attached to the grounding device described in FIG. 2a via a pivotjoint 2072. This comprises the second degree-of-freedom of rotation ofthe interface 2060. Inside the inner ring 2064 resides an attachment2078 which serves to affix the interface 2060 to the force-feedbackmeans which is the main subject of this invention. For clarity, theforce-feedback means is omitted. The attachment 2078 is connected to theforce-feedback. The attachment 2078 interfaces with the inner ring via aset of three or more wheel-like rotational mechanisms 2080, 2082 and2084. These rotational mechanisms let the backplate 2078 rotate withrespect to the inner ring 2064 and form the third degree-of-freedom ofrotation of the interface 2060. It is desirable to add a sensing meansto each of the degrees-of-freedom in order to determine the orientationof the hand in space. These sensing means may include, but are notlimited to, encoders, potentiometers, Hall-Effect sensors and the like.The figure illustrates how such sensing means may be positioned on theinterface 2060. An angular-position-sensing means 2070 can be affixed tothe pivot joint 2068 in order to measure the angular position of theinner ring 2064 with respect to the outer ring. Similarly, anangular-position-sensing means 2090 can be affixed to the pivot joint2072 in order to measure the angular position of the outer ring 2062with respect to the grounding device 2074. Finally, anangular-position-sensing means 2086 can be affixed to one of therotational mechanisms 2084 in order to measure the angular position ofthe attachment 2078 with respect to the inner ring 2064.

In operation, the articulated interface 2060 operates in a mannersimilar to the interface described in FIG. 2b.

For further understanding of the device, we now refer to the embodimentin FIG. 3 which shows a particular embodiment of the hand-force-feedbackdevice 300 which is worn over an instrumented glove 301 capable ofmeasuring the position of the hand. In this embodiment, a mechanicalsuperstructure capable of exerting forces on the thumb is shown whilethe structures that would be used for the other fingers are omitted forclarity. The device 300 comprises a superstructure having a front cam302 and a rear cam 304, a connecting link 306, a cam-supportingstructure 308, and an attachment 310 from the cam-supporting structure308 to a back plate 312. For exerting forces at the fingertip, a forceapplicator 316 to which is attached a tendon 318, is used. The forceapplicator 316 may employ any one of multiple ways of applying forces tothe fingertips. For example, forces may be applied to the fingertips asshown and described in U.S. Pat. No. 5,631,861 (where they are referredto as “feedback assemblies”), the contents of which are incorporated intheir entirety herein by reference as if explicitly included.

In one embodiment, it is desirable to include a force-sensing means inthe force applicator, as described in the aforementioned U.S. Pat. No.5,631,861. The force applicator may also be a thimble-like cup, or evena loop which fits around the fingertip. The tendon 318 is routed in aguiding groove at the top of the front cam 302 passing through both arigid tendon guide 320 and, optionally, a flexible tendon guide 322.From the flexible tendon guide 322, the tendon 318 continues through agroove at the top of the rear cam 304 and into the tendon casing 324,which is affixed to the back of the cam-supporting structure 308. Inorder to track the adduction/abduction movement of the thumb base joint,the cam supporting structure 308 is free to rotate with respect to theattachment 310 by means of a revolute joint 326. Furthermore, theattachment 310 connects to the back plate 312 by means of a fastener328, which enables the user to position the cam supporting structure 308at the base of the thumb. The backplate 312 is attached to the hand byany convenient means, such as straps, belts, tape, or the like. Inaddition, the front cam 302 attaches to the middle phalanx of the thumbby an attachment device 330, which may be any convenient means, such asa strap or belt. Conveniently, the front cam may be mounted on a base332 to which the attachment means 330 is attached.

In operation, the mechanical superstructure allows the tendon 318 to berouted to the force applicator 316, regardless of thumb configuration orposition and without hindering movement of the thumb. As the thumb isflexed the entire superstructure will move to track the thumb'smovement. When tension is exerted upon the tendon, a resistive forcewill be applied to the fingertip by the force applicator 316 and thesuperstructure will produce reactive forces on the back of the thumb bypressing down on the attached portions and thus producing reactivetorques at the joints. The connecting link 306 maintains alignmentbetween the front cam 302 and the rear cam 304 during movement of thethumb. As illustrated in the embodiment of FIG. 3, the connecting linkis straight, but it can be designed to have a curved or angular profilethat better conforms to the shape of the finger when it is flexed. Therigid tendon guides 314 and 320 and the flexible tendon guide 322 ensurethat the tendon remains in the cam groove. The flexible tendon guide322, for example, a flexible spring wire, can retract out of the way ofthe rear cam 304 as the thumb is hyper-extended. This will be furtherexpanded upon when the invention is described relative to the embodimentin FIG. 5a and FIG. 5b.

In the embodiment depicted in FIG. 3, the instrumented glove 301 is usedto obtain information on the position of the hand. Such information isrequired by the force-control unit in order to determine the force thatshould be exerted at the fingertip. Using a mechanical superstructuresuch as the one described in FIG. 3, it is also possible to forego usingthe instrumented glove altogether in favor of angular position sensingmeans incorporated directly into the superstructure. In this FIG. 3embodiment, these position sensing means could be located at the threepivot points, namely the joints 334 and 336 at each end of theconnecting link 306, and the pivot point 338 at the base of the rear cam304. Examples of angular-position-sensing means include, but are notlimited to, any devices which provides body-part position and/ororientation: mechanical, electrical, optical, strain gage,electromagnetic, ultrasonic, piezoelectric, Hall-effect, infraredemitter/detector pair, encoder/potentiometer, laser scanning or otherposition and/or orientation sensors.

FIG. 4a shows an embodiment of the hand-force-feedback-device 400 whichis worn over an instrumented glove 401 capable of measuring the positionof the hand. Alternatively, angular position sensing means can belocated directly in the superstructure as described in FIG. 3. In thisembodiment, a mechanical superstructure capable of exerting forces onthe index finger is shown while the structures that would be used forthe other fingers are omitted for clarity. The device 400 comprises asuperstructure having a front cam 402 and a rear cam 404, a connectinglink 406, a cam supporting structure 408, and an attachment 410 from thecam supporting structure 408 to a backplate 412. For exerting forces atthe fingertip, a force applicator 416 (see also 316 in FIG. 3) to whichis attached a tendon 418, is used. The tendon 418 is routed in a guidinggroove at the top of the front cam 402 passing through both rigid tendonguides 414 and 420 and an optional flexible tendon guide 422. From theflexible tendon guide 422, the tendon 418 continues through a groove atthe top of the rear cam 404 and into the tendon casing 424, which isaffixed to the back of the cam supporting structure 408. In order totrack the adduction/abduction movement of the index finger base joint,the cam supporting structure 408 is free to rotate with respect to theattachment 410 by means of a revolute joint 426. The backplate 412 isattached to the hand by any convenient means 428, such as straps, beltsor the like. In addition, the front cam 402 attaches to the middlephalanx of the finger by an attachment device 430, which may be anyconvenient means, such as a strap or belt. Conveniently, the front camis supported by a base 432 to which the attachment device 430 isattached. In operation, the mechanical superstructure functions in amanner similar to the one for the structure described in FIG. 3.

FIG. 4b is a perspective view of the embodiment of the invention that isdescribed in FIGS. 3 and 4a. Whereas the devices in FIGS. 3 and 4a showstructures implemented on a single finger, the device 450 in this figureillustrates a mechanism with force-feedback structures (452, 454, 456,458, 460) on each of the five fingers of the hand. A simplified versionof device 450 can be implemented with, for example, structures on thethumb 460, the index 458 and the middle finger 456.

We now direct our discussion to the structures illustrated in FIG. 5.FIGS. 5a, 5 b and 5 c serve to illustrate how the tendons are kept atopthe cams in the embodiments described herein. More particularly, FIG. 5ashows a mechanical superstructure 500 for a single finger 501 for aflexed finger, and serves to illustrate the functionality of theflexible tendon guide 502 which, in conjunction with the rigid tendonguides 504 and 505 and the cam supporting structure 506, helps keep thetendon 508 in the grooves located on the front 510 and rear 512 cams.When the finger is flexed, the flexible tendon guide springs up intoposition and helps guide the tendon 508 into the grove atop the cam.

The structure illustrated in FIG. 5b shows the mechanical superstructuredepicted in FIG. 5a in the case where the finger 501 is hyper-extendedinstead of flexed. In this case, the flexible tendon guide 502 bends outof the way once it makes contact with the rear cam 512. The structureillustrated in FIG. 5c shows a perspective view of a front cam 510 whichincludes both rigid 55 and flexible 502 tendon guides. The embodiment inFIG. 5c also shows how a groove 520 can be included atop a cam-likestructure 510 to further help guide the tendon 508 to the fingertip. Inoperation, the tendon slides back and forth in the groove as the fingeris flexed and extended.

With respect to the illustration in FIG. 6, there is shown an embodimentof the invention in which a mechanical structure 600 operates in amanner similar to the one described relative to the embodiment in FIG.4a but includes a different force applicator 602. Only the structure forthe index finger 601 is represented in the illustration to preserveclarity, but the structure could be repeated for some or for all of thefour other fingers. In this case, the force applicator 602 is designedsuch that it is not in contact with the fingertip until simulatedcontact forces are required. Force applicators are also described inU.S. Pat. No. 5,631,861 where they are referred to as “feedbackassemblies.” These designs have been adapted to make use of the frontcam 604 as a means to attach to the finger 601.

The force-applicator structure 602 consists of a force pad 606 (whichcan be fitted with force-sensing means), a structure support 608 and acontact spring 610. In this implementation, when there is little or notension in the tendon 612, the contact spring 610 pushes on theforce-applicator structure 602 such that the structure support 608touches the back of the fingertip (nail area). If the finger is flexed,the force applicator structure 602 moves accordingly, thus keeping theforce pad 606 a small distance away from the fingertip. When is itdesired to exert a force on the fingertip, the tension in the tendon 612overcomes the force of the contact spring and the force pad 606 makescontact with the fingertip. By keeping the force pad 606 away from thefingertip until force is applied, bandwidth requirements of the forceapplying means are reduced.

For example, when the invention is used to provide feedback from avirtual environment and a virtual object is grasped, the force pad makescontact with the fingertip with a non-zero relative velocity, as would areal object when contacting the fingertip. If the force pad were alwaysin contact with the fingertip, much larger tendon velocities andaccelerations would have to be generated to provide the same contactsensation to the user. In operation, the rest of the mechanicalsuperstructure functions in a manner similar to the behavior of thestructure described in FIG. 3 and is not described further.

Another embodiment of the invention is illustrated in FIG. 7a, whichutilizes a simplified cam-based superstructure 700 requiring fewermoving parts which is worn over an instrumented glove 702 capable ofmeasuring hand position. In this embodiment, a mechanical superstructurecapable of exerting forces on the index finger is shown while thestructures that would be used for the other fingers are omitted forclarity. The device 700 comprises a superstructure having a front can706 with front 710 and rear 712 tendon guides, a rear cam 708 with front714 and rear 716 tendon guides and a base support 718 which anchors thetendon casing 720. For exerting forces at the fingertip, a forceapplicator 722 to which is attached a tendon 724, is used. The tendon724 is routed in a guiding groove at the top of the front cam 706passing through tendon guides 710 and 712 and a guiding groove at thetop of the rear cam 708 passing through tendon guides 714 and 716. Fromthe rear cam 708, the tendon 724 goes into the tendon casing 720, whichis affixed to the back of the base support 718, which in turn isattached to a backplate 726 for added stability. The backplate 726 isattached to the hand by any convenient means 728, such as straps, belts,or the like. In addition, the front cam 706 attaches to the middlephalanx of the finger by an attachment device 732, which may be anyconvenient means, such as a strap or belt. Conveniently, the front cammay be mounted on a base 730 to which the attachment means 732 isaffixed. Similarly, the rear cam 708 attaches to the proximal phalanx ofthe finger by an attachment device 736, which may be any convenientmeans, such as a strap or belt. Again, the rear cam 708 may be mountedon a base 734 to which the attachment means 736 is fixed.

An end view of an embodiment of one of the tendon guides is illustratedin FIG. 7b. It illustrates how the guide 750 keeps the tendon 752aligned with the grove of the cam 754 while still letting it breakcontact with the cam when the finger is hyper-extended.

In operation, the instrumented glove 702 acts as the position-sensingmeans for the device. Under little or no tendon force, the finger isfree to move and flex in any direction while the position sensing in thehand ensures that the tendon slack will be kept to a minimum, ensuringprompt response when forces are desired at the fingertip. Forces andtorques are transmitted to the fingertip and joints respectively in amanner similar to the one described in FIG. 4a.

FIGS. 8a-8 e are side views of four different exemplary embodiments offront cams for the embodiments of the devices depicted in FIGS. 3-7. Asmentioned in the description of the invention relative to the embodimentin FIG. 3, it is possible to include a force-sensing means in the forceapplicator located at the fingertip. An alternate way of measuring theforces applied at the fingertip is to measure the tension in the tendonas it leaves the front cam.

FIG. 8a is an illustration showing an exemplary cam-based force sensorincorporated into the front cam 800. In this embodiment, a small flexure802 is machined into the cam pattern and a small pulley-like device 804is attached to the end of the flexure 802. The tendon 808 slides in agroove machined into the cam, goes around the pulley 804 and then backup onto the groove. An increase in tension in the tendon 808 causes theflexure 802 to bend and a deflection sensing means 806 (such as a straingauge) attached to the flexure measures the deflection. By measuring thedeflection of the flexure and knowing its stiffness, it is possible todetermine the tension in the tendon and thus the force exerted at thefingertip.

FIG. 8b is an illustration showing an exemplary cam-based force sensorincorporated into the front cam 820, where a detour 822 is included inthe tendon path on the front cam such that the tendon 826 must go arounda specific point where a force-measuring device 824, such as a loadcell, can be located. The force measured by the force-measuring device824 will be proportional to the tension in the tendon 826 and thus tothe force exerted at the fingertip.

FIG. 8c is an illustration showing an exemplary cam-based force sensorincorporated into the front cam 840, where the tendon 848 is redirectedfrom it's intended path in a groove atop the front cam 840 such that itpasses around a pulley-like device 846 mounted on a flexure 842 which isattached to the inside of the front cam, before returning back to itsintended path in the groove atop the front cam 840. Using this approach,the tension in the tendon 848 will produce a force on the pulley whichwill be nominally perpendicular to the flexure 842, and thus produce adeflection which is proportional to the force. A deflection sensingmeans 844 (such as a strain gauge) attached to the flexure 842 measuressaid deflection. By measuring the deflection of the flexure and knowingits stiffness, it is possible to determine the tension in the tendon 868and thus the force exerted at the fingertip.

FIG. 8d is an illustration showing an exemplary cam-based force sensorincorporated into the front cam 860, where the tendon 868 is redirectedfrom it's intended path in a groove atop the front cam 860 such that itpasses around a pulley-like device 866 located inside the front cam 860.Also, a flexure 862 is incorporated into the top part of the front camsuch that the tendon 868 slides over the flexure. The effect ofrerouting the tendon 868 around the firmly-anchored pulley-like device866 produces a deflection in the flexure 862 when the tendon is undertension. A deflection-sensing means 864 (such as a strain gauge)attached to the flexure 862 measures the deflection. By measuring thedeflection of the flexure and knowing its stiffness, it is possible todetermine the tension in the tendon 868 and thus the force exerted atthe fingertip.

FIG. 8e is an illustration showing an exemplary cam-based force sensorincorporated into the front cam 880, where the tendon 888 passes over apulley-like device 886 before leaving the front cam 860. A flexure 882is incorporated into the top part of the front cam such that the tendon868 deflects the flexure when in tension. A deflection-sensing means 884(such as a strain gauge) attached to the flexure 882 measures thedeflection. By measuring the deflection of the flexure and knowing itsstiffness, it is possible to determine the tension in the tendon 888 andthus the force exerted at the fingertip.

Yet another embodiment of a hand force-feedback device 900 which is wornover an instrumented glove 902 capable of measuring the position of thehand is now described relative to the illustration in FIG. 9. In thisparticular embodiment, a mechanical superstructure using a plurality oftendons and capable of exerting a force at the fingertip and torques ateach of the three joints of the index finger is shown. The individualstructures that would be used for the other fingers are omitted forclarity. In this embodiment, three force-generating means, such as theone already described relative to the embodiment illustrated in FIG. 1,are required per finger. Forces are transmitted from the forcetransmitting means to the superstructure on the finger via tendons 904,906 and 908 which are routed through tendon casings 910, 912 and 914,respectively. A base tower 916 anchors tendon casing 910 which housestendon 904 which in turn terminates at tower 922. Similarly, tower 922anchors tendon casing 912 which houses tendon 906 which in turnterminates at tower 924. Finally, tower 924 anchors tendon casing 914which houses tendon 908 which in turn terminates at the force applicator926 located at the fingertip. The base tower is mounted on a rigid basesuch as a backplate 918 which in turn is attached to the hand by anyconvenient means, such as straps, belts or the like 920. In addition,tower 922 attaches to the proximal phalanx of the index finger by anattachment device 930, which may be any convenient means, such as astrap or a belt. Conveniently, tower 922 may be mounted on a base 928 towhich the attachment device 930 is attached. Similarly, tower 924attaches to the middle phalanx of the index finger by an attachmentdevice 934 and may also be mounted on a base 932 to which the attachmentdevice 934 is attached.

In operation, the mechanical superstructure, used in conjunction with aninstrumented glove 902, makes it possible to exert individuallycontrolled resistive torques at each of the finger joints and aresistive force at the fingertip. By applying a tension in tendon 904,it is possible to pull on tower 922 which acts as a moment arm andproduces a torque at the base joint 936 of the finger. Similarly, byapplying a tension in tendon 906, it is possible to pull on tower 924which acts as a moment arm and produces a torque at the middle joint 938of the finger. Finally, by applying a tension in tendon 908, it ispossible to pull on the force applicator 926 which produces a torque atthe distal joint 940 of the finger while also producing a resistiveforce at the fingertip 926.

In FIG. 10a there is illustrated another embodiment of the handforce-feedback device. In this embodiment, a mechanical superstructure1000 capable of exerting a force at the tip of the index finger isshown. The individual structures that would be used for the otherfingers are omitted for clarity. The superstructure is designed to beworn over an instrumented glove 1002 capable of measuring the positionof the hand. Forces are transmitted from the force-transmitting means tothe superstructure on the finger via a tendon 1014 which is routedthrough a tendon casings 1012. A tendon-supporting tower 1004 extendsabove the finger and serves as the end point for the tendon casing 1012.The tendon 1014 exits the tendon casing and then ends at a forceapplicator 1016 which enables it to exert forces on the fingertip. Tominimizes friction, a pulley-type device 1010 or the like may be used toroute the tendon over the end of the tower. The tower 1004 is mounted ona rigid base such as a backplate 1006 which in turn is attached to thehand by any convenient means, such as straps, belts or the like 1008.

In operation, the tower structure keeps the tendon 1014 above the fingersuch that it can exert a resistive force on the force applicator 1016for any given finger configuration. In this and the other embodimentsdescribed heretofore, the towers also. cooperate with the cams toaugment or enhance the moment arm and provide moment augmenting means.It the illustrated configuration, the mechanical superstructure 1000resides above the finger in a plane which coincides with the plane ofmotion of the finger when it is flexing. Additional superstructures maybe added which reside in different planes in order to exert forces inanother plane, such as the plane where finger adduction/abductionoccurs. By combining two or more of the described superstructures forone finger, it is possible to produce resulting three-dimensionalforces.

FIG. 10b shows another embodiment of the hand force-feedback devicedescribed in FIG. 10a where an additional. In this embodiment, amechanical superstructure 1030 capable of exerting a force at the tip ofthe index finger is shown. The superstructure consists of two individualtower structures 1032 and 1034 and serves to illustrate how multiplestructure can be used in conjunction with one another to provide morecomplex force feedback to the user.

In operation, tower structure 1032 keeps the tendon 1036 above thefinger such that it can exert a resistive force on the force applicator1038 for any given finger configuration. In the illustratedconfiguration, tower structure 1032 resides above the finger in a planewhich coincides with the plane of motion of the finger when it isflexing. An additional tower structure .1034 is shown and it resides ina plane which is perpendicular to the plane in which the other towerstructure 1032 resides. The tower structure 1034 routes the tendon 1040to the force applicator 1038 where it may exert side forces on thefinger. By exerting forces with both force-feedback structuressimultaneously, it is possible to produce complex forces which actoutside the planes of both structures.

FIG. 10c is a perspective view of the embodiment of the invention thatis described in FIGS. 10a and 10 b. Whereas the devices in FIGS. 10a and10 b show structures implemented on a single finger, the device 1050 inthis figure illustrates a mechanism with force-feedback structures(1052, 1054, 1056, 1058, 1060) on each of the five fingers of the hand.A simplified version of the device 1050 can be implemented with, forexample, structures on the thumb 1060, the index 1058 and the middlefinger 1056.

In FIG. 11a, yet another embodiment of the hand-force-feedback device isillustrated. In this embodiment, a mechanical superstructure 1100 isaffixed to the back of the hand and serves two roles: housingfinger-joint-angle-sensing means 1121, and routing the force-applyingtendons 1110 to the fingertips. Alternatively, thejoint-angle-sensing-means can be omitted from the superstructure infavor of an instrumented glove 1120 capable of measuring hand position.In this illustration, the superstructure is shown for the index fingerwhile the similar individual structures which may be used for the otherfingers are omitted for clarity. The superstructure comprises aplurality of support towers 1114 through which passes a sliding tendoncasing 1112 and which are linked together via a common flexible base1113. The flexible base can be made of a spring steel, rubber, plastic,composite material, or any other appropriate material and can bedesigned in such a way that there are guiding pockets for bend sensors1121 (e.g. the strain-gage bend sensor of Kramer et al.) located aboveeach of the finger joints. In addition, the flexible base attaches tothe finger using attachment devices 1118, which may be any convenientmeans, such as a strap or a belt. The support towers 1114 can be eitherattached to the flexible base 1113 if spring steel is used, or moldedinto it if rubber or plastic is used. The sliding tendon casing isanchored at the support tower 1115 closest to the fingertip but free toslide through holes in the other support towers 1114. The tendon whichtransmits forces to the force applicator at the fingertip 1116 is routedfrom the force-applying means described relative to the embodimentillustrated in FIG. 1 to the superstructure 1100 via a tendon casing1102 which is anchored at a base support 1104. The base support may bemounted on a rigid backplate 1106 which in turn is attached to the handby any convenient means 1108 such as straps, belts or the like.

FIG. 11b shows an end view of one of the support towers 1122 alreadyshown and described relative to the embodiment in FIG. 11a, and showsthe chamfered hole 1124 through which the sliding tendon casing moves.In this embodiment, all the support towers have the same height but itmight also be desirable to vary the heights to change the distributionof the forces on the finger.

In operation, the sliding tendon casing 1112 is free to move relative tothe holes in the support towers 1114 and it's purpose is to provide asmooth arced path for the tendon 1110 from the base support 1104 to theforce applicator 1116 located at the fingertip. The joint-sensing means1121 located in the flexible base 1113, or the instrumented glove 1120if it is used instead, serve to measure the flexion in the finger ateach of its joints. The mechanical superstructure allows the tendon 1110to be routed to the force applicator 1116, regardless of fingerconfiguration or position and without hindering movement of the finger.As the finger is flexed the entire superstructure will move to track thefinger's movement. When tension is exerted upon the tendon, a resistiveforce will be applied to the fingertip by the force applicator 1116 andthe superstructure will produce reactive forces on the back of thefinger by pressing down on it and thus producing reactive torques at thejoints.

In FIG. 12a, we turn our attention to an embodiment of the inventionthat operates in a manner similar to the one illustrated in FIG. 11a.However, the embodiment illustrated in FIG. 12a differs in two primaryrespects from the embodiment in FIG. 11a. First, in FIG. 12a, tendon1202 is routed through the support towers 1204 without the use of asliding tendon casing such as the one depicted in FIG. 11a. The seconddifference is that the support towers 1204 are of varying height, unlikethe support towers depicted in FIG. 11a which all have substantially thesame height.

In FIG. 12b, there is illustrated an end view of one of the supporttowers 1207 illustrated FIG. 12a, and further shows the chamfered hole1208 through which the sliding tendon moves. In operation, the device1200 will function much like device 1100 in FIG. 11a, except that theresulting torques exerted at the finger joints are distributed somewhatdifferently, with larger torques exerted at the joints nearest to thebase support 1206.

FIG. 12c is a perspective view of the embodiment of the invention thatis described in FIGS. 12a and 12 b. Whereas the device in FIGS. 12a and12 b shows a structure implemented on a single finger, the device 1220in this figure illustrates a mechanism with force-feedback structures(1222, 1224, 1226, 1228, 1230) on each of the five fingers of the hand.A simplified version of the device 1220 can be implemented with, forexample, structures on the thumb 1230, the index 1228 and the middlefinger 1226.

A variation of the embodiment of the structure in FIG. 7 is illustratedin FIG. 13a. The grooves in the front and rear cams used in the FIG. 7embodiment, and detailed in FIG. 5c, can essentially be thought of as aninfinite number of rollers placed side by side atop the cam to helpguide the tendon to the fingertip with minimal friction. Asuperstructure 1300 is shown where a discrete number of rollers 1302 areused to guide the tendon 1318 instead of a continuous groove. In thisinstance, three rollers are used, but more or fewer rollers may beemployed to provide the desired functionality, and any given quantitydeemed adequate may be used. The device may be worn over an.instrumented glove 1304 capable of measuring hand position. In thisembodiment, a mechanical superstructure capable of exerting forces onthe index finger is shown while similar structures which may be used forthe other fingers are omitted for clarity. The device 1300 comprises asuperstructure having a front tower 1306 with front 1308 and rear 1310tendon guides and three rollers 1302; a rear tower 1312 with front 1314and rear 1316 tendon guides, and three rollers 1302; and a base support1322 which anchors the tendon casing 1324. A connecting means 1320 suchas the two links shown in the figure may be used to help ensure that thetowers 1306 and 1312 remain aligned with one another. Similarly, such aconnecting means may be used to connect the rear tower 13 12 to the basesupport 1322. When such an implementation is used, joint-sensing means(for example, encoders, potentiometers, electromagnetic sensors, and thelike) may be positioned at the link joints thus removing the need for aninstrumented glove 1304 to measure hand position. For exerting forces atthe fingertip, a force applicator 1319 to which is attached a tendon1318, is used. The tendon 1318 is routed along the pulleys 1302 at thetop of front tower 1306 and passing through tendon guides 1308 and 1310and the pulleys at the top of rear tower 1312 passing through tendonguides 1314 and 1316. From the rear tower, the tendon goes into thetendon casing 1324, which is affixed to the back of the base support1322, which in turn may be attached to a backplate 1326 for addedstability. The backplate 1326 is attached to the hand by any convenientmeans 1328, such as straps, belts or the like. In addition, the frontand rear towers attach to the phalanges of the finger by attachmentdevices 1328, which may be any convenient means, such as a strap orbelt. Conveniently, the front and rear towers may be mounted on bases1330 to which the attachment means 1328 are fixed.

An end view of one of the tendon guides depicted in FIG. 13a isillustrated in FIG. 13b. It illustrates how the guide 1332 keeps thetendon 1334 aligned with the groove of the pulley 1336 while stillletting it break contact with the pulley when the finger ishyper-extended.

In operation, the instrumented glove 1304 of FIG. 13, acts as theposition-sensing means for the device. Under little or no tendon force,the finger is free to move and flex in any direction while the positionsensing in the hand ensures-that the tendon slack will be kept to aminimum, ensuring prompt response when forces are desired at thefingertip. Forces and torques are transmitted to the fingertip andjoints respectively in a manner similar to the one described in FIG. 4aand are not described further here.

FIG. 14a is an illustration showing an embodiment of the invention whichuses a superstructure 1400 which exerts a force directly at thefingertip without attaching to other parts of the finger. In thisembodiment, a mechanical superstructure capable of exerting forces onthe index finger 1406 is shown while similar structures which may beused for the other fingers are omitted for clarity. At the heart of thesuperstructure is a five-bar linkage consisting of links 1407, 1408,1409 and 1410 which are attached together via revolute joints 1405. Link1409 extends to a linear adjustment 1415 which attaches to another link1411 which is attached to the force applicator 1404 at the fingertip.Links 1407 and 1408 are attached to pulleys 1412 and 1413, respectively.Pulley 1413 cannot be seen in the illustration as it is located directlybehind pulley 1412 but it is shown in the perspective view of FIG. 15a.Links 1407 and 1408 and pulleys 1412 and 1413 are attached to, and pivotabout, a support 1414. The support is also free to rotate about joint1416 to track finger abduction/adduction. The support is connected tothe backplate 1420 via the joint 1416 and the backplate is attached tothe hand by any convenient means 1422 such as straps, belts or the like.Two tendons 1424 and 1426, one of which is not visible, are routedaround, and fixed to, the two pulleys 1412 and 1413, respectively. Thetendons are guided to the superstructure 1400 from the force-producingmeans as described relative to FIG. 1 using four tendon casings 1418, ofwhich two can be seen in the illustration. Alternatively, incompressibleyet flexible tendons such as steel wire may be used, wherein only twotendon casings 1418 are required because the tendons 1424, 1426 are thusable to both push and pull on the pulleys.

In operation, the mechanism is capable of fully tracking the motion ofthe finger when no forces are being exerted. To exerted forces, thetorques on the pulleys 1424, 1426 are exerted via the tendons 1424,1426, and these torques are translated to forces exerted at thefingertips via the five-bar linkage. Using this mechanism, it ispossible to exert a force in any direction in the plane of the finger.Additionally, it may be desirable to add another pulley/tendon assemblyto joint 1416 in order to exert resistive forces when the finger isabducting/adducting. By including a position-sensing means (e.g.,encoder, potentiometer, Hall-effect sensor) at the force-applying means(e.g., DC motor, stepper motor, pneumatic actuator) it is possible tocompute the position of the force applicator 1404 and therefore thefingertip, thus removing the need for an instrumented glove 1402 when itis not otherwise desired. The linear adjustment 1415 may befriction-based or indexed and serves to adjust the mechanism for avariety of hand sizes.

FIG. 14b is an embodiment of the invention that is very similar to thedevice illustrated in FIG. 14a but adds an additional degree-of-freedomof force feedback. In this embodiment, a mechanical superstructurecapable of exerting forces on the index finger is shown while similarstructures which may be used for the other fingers are omitted forclarity. The device 1450 is designed such that an additional pulleyassembly is added to the superstructure described in FIG. 14a. Thepulley assembly consists of a pulley 1452, which is mounted at the pivotjoint 1454, a tendon 1456 which wraps around the pulley and is routedinto the tendon casing support 1458, and two tendon casings 1460 (one isvisible) which are anchored into the casing support and serve as theforce transmitting means from the force-producing means to the forceapplying means. The pulley 1452 is fixed to the pivot joint 1454, whichin turn is fixed to the support 1462. They cannot move with respect toone another. The pivot joint 1454, and consequently the pulley 1452 andthe support 1462, can rotate with respect to the backplate 1464.

In operation, device 1450 is capable of exerting the forces described inFIG. 14a as well as forces in the abduction/adduction plane of thefinger by rotating the pulley 1452 about the pivot joint 1454. The netresult is that complex 3-dimensional forces can be transmitted to thefingertips via the force applicator 1466.

FIG. 15a shows a perspective view of the same embodiment of theinvention that is shown in plan view and described relative to FIG. 14a.It shows the second pulley 1513 (1413 in FIG. 14a) located behind thepulley 1512 (1412 in FIG. 14a). It also shows an unobstructed view ofthe four tendon casings 1518 (1418 in FIG. 14a). Pulley 1512 is attachedto link 1508 of the five-bar linkage while pulley 1513 is attached tolink 1507.

FIG. 15b is a perspective view of the embodiment of the invention thatis described in FIGS. 14a and 15 a. Whereas the devices in FIGS. 14a and15 a show a structure implemented on a single finger, the device 1530 inthis figure illustrates a mechanism with force-feedback structures(1532, 1534, 1536, 1538, 1540) on each of the five fingers of the hand.A simplified version of the device 1530 can be implemented with, forexample, structures on the thumb 1540, the index 1538 and the middlefinger 1536.

FIG. 15c is an embodiment of the invention that uses a superstructure1550 which exerts a force directly at the fingertip without attaching toother parts of the finger. As for the other mechanism described herein,the embodiment is shown for the index finger but it can be extended tothe other fingers of the hand. It's operation is very similar to that ofthe device described in FIG. 14a. The difference is that the mechanismcomprises two five-bar linkages instead of one. In this embodiment, thefirst five-bar linkage consists of two straight links 1552 and 1554, atriangular link 1556 and a v-shaped link 1558. The triangular link andthe v-shaped link are also part of the second five-bar linkage whichalso consists of the straight link 1560 and another v-shaped link 1562which attaches to the force applicator 1564 at one end. In this type ofconfiguration, the second five-bar linkage mimics the motion of thefirst one, which is actuated as described in FIG. 14a. A third five-barlinkage could be added in series if so desired.

In operation, the mechanism behaves in a manner that is very similar tothe mechanism described in FIG. 14a. The advantage of adding a secondfive-bar linkage is that for the full range-of-motion of the hand, thedevice 1550 keeps a lower profile than the one described in FIG. 14a. Itwill be able stay close to the index finger 1566 when the user makes afist yet not extend high above the finger when it is hyper-extended.Additionally, the structure is free to rotate 1570 about a joint 1568that enables it to track finger adduction/abduction without hinderingit. It may be desirable to add another pulley/tendon assembly to exertadduction and abduction forces at the fingertip.

FIG. 16a is a variation of the embodiment of the invention described inFIG. 14a. It also exerts forces directly to the force applicator 1602located at the fingertip, but instead of using a five-bar linkage totransmit the forces, it uses a tendon-based approach. Again, thesuperstructure 1600 is shown for the index finger, with the similarstructures that may be used for the other fingers omitted for clarity.The tendon-based approach used in this mechanism acts similarly to thefive-bar linkage in FIG. 14a except that the five-bar mechanism isreplaced with a pair of pulleys 1608 and 1610 and a tendon 1604 which isanchored at both pulleys. A base link 1606 supports both pulleys 1608and 1610 which are free to rotate about their respective joint shafts1614 and 1616. Additionally, pulley 1610 is attached to link 1612 suchthat when it rotates, link 1612 rotates with respect to the base link1606. Similarly, pulley 1608 rotates about shaft 1614 but is connectedto pulley 1610 via tendon 1604 such that any rotation of pulley 1608causes a corresponding rotation in pulley 1610. The mechanism includestwo other pulleys 1618 and 1620 which correspond to pulleys 1412 and1413 respectively in FIG. 14a. Pulley 1618 is attached to the base link1606 and is free to rotate about shaft 1614 such that when the pulleyrotates, the base link rotates with respect to the support 1622.Similarly, pulley 1620 is attached to pulley 1608 and is free to rotateabout shaft 1614 such that when pulley 1620 rotates, it cause acorresponding rotation in pulley 1608 and consequently a rotation inpulley 1610.

In operation, the mechanism behaves like the mechanism described in FIG.14a where rotating the bases pulleys 1618 and 1620 using tendons 1624and 1626 causes forces to be produced at the force applicator 1602located at the fingertip.

FIG. 16b is a perspective view of the embodiment of the invention thatis described in FIG. 16a. Whereas the device in FIG. 16a shows astructure implemented on a single finger, the device 1630 in this figureillustrates a mechanism with force-feedback structures (1632, 1634,1636, 1638, 1640) on each of the five fingers of the hand. A simplifiedversion of the device 1630 can be implemented with, for example,structures on the thumb 1640, the index 1638 and the middle finger 1636.

FIG. 16c is an embodiment of the invention that is very similar to thedevice illustrated in FIG. 16a but adds an additional degree-of-freedomof force feedback. In this embodiment, a mechanical superstructurecapable of exerting forces on the index finger is shown while similarstructures which may be used for the other fingers are omitted forclarity. The device 1660 is designed such that an additional pulleyassembly is added to the superstructure described in FIG. 16a. Thepulley assembly consists of a pulley 1662, which is mounted at the pivotjoint 1664, a tendon 1666 which wraps around the pulley and is routedinto the tendon casing support 1668, and two tendon casings 1670 (one isvisible) which are anchored into the casing support and serve as theforce transmitting means from the force-producing means to the forceapplying means. The pulley 1662 is fixed to the pivot joint 1664, whichin turn is fixed to the support 1672. They cannot move with respect toone another. The pivot joint 1664, and consequently the pulley 1662 andthe support 1672, can rotate with respect to the backplate 1674.

In operation, device 1660 is capable of exerting the forces described inFIG. 16a as well as forces in the abduction/adduction plane of thefinger by rotating the pulley 1662 about the pivot joint 1664. The netresult is that complex 3-dimensional forces can be transmitted to thefingertips via the force applicator 1676.

FIG. 17 illustrates an embodiment of the invention which utilizes acam-based superstructure 1700 requiring few moving parts which is wornover an instrumented glove 1702 capable of measuring hand position. Inthis embodiment, a mechanical superstructure capable of exerting forceson the index finger is shown while the structures that would be used forthe other fingers are omitted for clarity. The device 1700 comprises asuperstructure having an offset front cam 1705 with front 1707 and rear1711 tendon guides, an offset middle cam 1706 with front 1710 and rear1712 tendon guides, an offset rear cam 1708 with front 1714 and rear1716 tendon guides and a base support 1718 which anchors the tendoncasing 1720 that serves as the force-transmitting means. For exertingforces at the fingertip, a force applicator 1722 to which is attached atendon 1724, is used. The tendon 1724 is routed in a guiding groove atthe top of the front cam 1705 passing through tendon guides 1707 and1711 and then in the guiding grooves at the top of the middle 1706 andrear 1708 cams, passing through their respective tendon guides. From therear cam 1708, the tendon 1724 goes into the tendon casing 1720, whichis affixed to the back of the base support. The base support 1718 isattached to the hand by any convenient means 1728, such as straps, beltsor the like. In addition, the front cam 705 attaches to the distalphalanx of the finger via the force applicator 1722. The middle cam 1706attaches to the middle phalanx by an attachment device 1732, which maybe any convenient means, such as a strap or belt. Conveniently, themiddle cam may be mounted on a base 1730 to which the attachment means1732 is affixed. Similarly, the rear cam 1708 attaches to the proximalphalanx of the finger by an attachment device 1736, which may be anyconvenient means, such as a strap or belt. Again, the rear cam 1708 maybe mounted on a base 1734 to which the attachment means 736 is fixed.

In operation, the instrumented glove 1702 acts as the position-sensingmeans for the device. Under little or no tendon force, the finger isfree to move and flex in any direction while the position sensing in thehand ensures that the tendon slack will be kept to a minimum, ensuringprompt response when forces are desired at the fingertip. Forces andtorques are transmitted to the fingertip and joints respectively using asingle tendon 1724 per finger. Under tension, the tendon will pull up onthe force applicator 1722 thus producing a reactive force at thefingertip. Simultaneously, the tendon will push down on the three offsetcams 1705, 1706 and 1708. This effect will produce reactive torques ateach of the three finger joints.

FIG. 18 illustrates an embodiment of the invention which utilizes acam-based superstructure 1800 which is worn over an instrumented glove1801 capable of measuring hand position. In this embodiment, amechanical superstructure capable of exerting forces on the index fingeris shown while the structures that would be used for the other fingersare omitted for clarity. The device 1800 comprises a superstructurehaving an offset front cam 1812, an offset middle cam 1810, an offsetrear cam 1808 and a base support 1822 which anchors the three tendoncasings 1824, 1826 and 1828 that serve as the force-transmitting means.For exerting forces at the fingertip and torques at the distal fingerjoint, a force applicator 1820 to which is attached a tendon 1806, isused. Conveniently, the tendon 1806 is routed around a pulley 1818 andthen through a guiding groove at the top of the front cam 1812 and thenthrough a flexible tendon casing 1816 which is anchored at the base ofthe middle offset cam 1810 at one end, and at the base support 1822 atthe other. For exerting torques at the middle finger joint, a tendon1804 which is fixed to the front of the middle cam 1810 is used. Thetendon 1804 is routed in a guiding groove at the top of the middle cam1810 and then through a flexible tendon casing 1814 which is anchored atthe base of the rear cam 1808 at one end, and at the base support 1822at the other. Finally, for exerting torques at the base finger joint, atendon 1802 which is fixed to the front of the rear cam 1810 is used.The tendon 1802 is routed in a guiding groove at the top of the rear cam1810 and then directly to the base support 1822 at the other. The threetendons 1806, 1804 and 1802 enter the base support 1822 on one side andexit into tendon casing 1824, 1826 and 1828 respectively on the other.The base support 1822 is attached to the hand by any convenient means1830, such as straps, belts or the like. In addition, the front cam 1812attaches to the distal phalanx of the finger via the force applicator1820. The middle cam 1810 attaches to the middle phalanx by anattachment device 1836, which may be any convenient means, such as astrap or belt. Conveniently, the middle cam may be mounted on a base1832 to which the attachment means 1836 is affixed. Similarly, the rearcam 1808 attaches to the proximal phalanx of the finger by an attachmentdevice 11838, which may be any convenient means, such as a strap orbelt. Again, the rear cam 1808 may be mounted on a base 1834 to whichthe attachment means 1838 is fixed.

In operation, the instrumented glove 1801 acts as the position-sensingmeans for the device. Under little or no tendon force, the finger isfree to move and flex in any direction while the position sensing in thehand ensures that the tendon slack will be kept to a minimum, ensuringprompt response when forces are desired at the fingertip. Forces andtorques are transmitted to the fingertip and joints respectively usingthree tendons 1806, 1804 and 1802 per finger. Under tension, tendon 1806will pull up on the force applicator 1820 thus producing a reactiveforce at the fingertip as well as a reactive force at the distal fingerjoint. Tendon 1804 will pull on the middle offset cam 1810 which willproduce a reactive torque at the middle finger joint. Similarly, tendon1802 will pull on the rear offset cam 1808 which will produce a reactivetorque at the proximal finger joint. Unlike the device presented in FIG.17, device 1800 makes it possible to control the torques and forcesbeing exerted at each joint individually.

FIGS. 19A and 19B are diagrammatic illustrations of a side cross-sectionand a perspective view of an illustrative embodiment of a motor-spoolassembly, which demonstrates how a motor may control tendon position.Motor 1900 with shaft 1901 is connected to spool shaft 1903 by optionalcoupler 1902. Shaft 1903 rotates in spool housing 1905 by bearings 1904.Tendon 1906 is wound around the shaft 1903.

FIG. 20 is a block diagram of a canonical motor-control system. Theprocessor 2000 provides a digital signal to the digital-to-analogconverter 2001, which outputs an analog voltage which is amplified bythe amplifier 2002 which powers the motor 2003. The motor may have anencoder, tachometer, or other rotation-monitoring means 2004, whichprovides a signal to the signal conditioner 2005. The signal-conditioneroutput is digitize by the analog-to-digital converter 2006, whichprovides the rotation information in digital form to the processor 2000.

FIGS. 21A and 21B are a longitudinal cross section of a flexible tendonin a useful embodiment of a flexible sheath tendon guide. FIG. 21A showsthe tendon-sheath structure unflexed, while FIG. 21B shows thetendon-sheath structure flexed. The sheath comprises a flexible innerlayer 2101, typically Teflon®, or any other lubricious, flexible,low-compressibility material through which the flexible, high-tensilestrength tendon 2100 passes. Surrounding the inner layer is a springwinding 2102 and 2104 which adds considerable compressive strength tothe sheath, while still allowing low resistance to flexing. Surroundingthe winding layer is a flexible encapsulating layer 2103, which preventsthe coils from buckling on top of one another, in addition to providinga smooth outer surface. In FIG. 21B, where the tendon-sheath structureis shown flexed from top to bottom, the top surface of the winding layer2102 is shown where the individual wires separate creating a space 2105when flexed, providing little resistance to bending. The bottom surfaceof the winding layer 2104 still has all wires firmly against oneanother, providing strong compressive strength.

FIGS. 22A-22E are diagrammatic illustrations showing various pinnedjoints which may be employed when routing a tendon 2200 from theactuator to its desired final destination. These “rigid” jointstructures provide an alternative to the flexible joint structuredescribed in FIGS. 21A and 22B. FIG. 22A comprises two links 2201 and2202 which are pinned together via a pin 2203. Each link typicallyencloses the tendon 2200, and may be of any convenient cross-sectionalshape, such as round or square. As shown, a pulley 2204 also rotatesabout this axis. The tendon 2200 passes across the pulley, and due tothe pulley's placement at the joint axis, the tendon will always passthrough the same location in each of the links independent of linkangle. A hole in each link endcap 2205 further guides the tendon. Thejoint angle between the two links may optionally be measured by anyconvenient means, such as an encoder, potentiometer, resolver, and thelike 2207, or a resistance-varying strain-sensing goniometer 2208, suchas provided by Kramer, U.S. Pat. No. 5,047,952. Among other things, theangle information may be used to correct for the change in tendon lengthas it passes along the pulley. Link-end surfaces 2206 may be made suchthat they press against each other and prevent the links fromsufficiently aligning, whereby the tendon could draw away from thepulley.

FIG. 22B is a top view, and FIG. 22C is an end cross-section view, wherea plurality of tendons 2212 are routed across a plurality of pulleys2213. Two links 2209 and 2210 are connected by pin 2211, which providesthe rotation axis for the pulleys 2213. When multiple tendons arerouted, each tendon as shown may represent an independently-controlledtendon. A pair of tendons as shown may also comprise a single tendon,where one visible tendon is moving from the actuator, while the pairedtendon is actually the returning portion of the tendon. Such aconfiguration is useful when it is desirable to have a tendon form acomplete loop.

FIG. 22D is a diagrammatic illustration where two links 2214 and 2215can pass through alignment without concern that the tendon 2221 mightlose contact with a guiding pulley. The two links 2214 and 2215 areshown pinned by joint 2216. The pulleys 2217 and 2218 are pinned torotate on the link 2215 via pins 2219 and 2220, respectively. With thisconfiguration, the path of the tendon relative to link 2215 remainsconstant, since that is the link to which the pulleys are attached.However, relative to link 2214, the path of the tendon varies with theangle of link 2215.

FIG. 22E is a diagrammatic illustration of a dual-tendon-guide pulleyarrangement. The principle of operation here is similar to the operationof FIG. 22D. Links 2222 and 2223 rotate relative to each other via pin2224. Pulley 2225 also rotates about that pin. There are two otherpulleys 2226 and 2227 which rotate on link 2223 via shafts 2228 and2229, respectively. Tendon 2230 is guided by pulleys 2225 and 2226,while tendon 2231 is guided by pulleys 2225 and 2227. As with FIG. 22D,when two pulleys are used, with one pulley on each side of the tendon,the links may align without concern that the tendon may lift fromcontact with a pulley. Various joint-angle sensor as previouslymentioned may again be used. The joint-angle information may also beused to correct for the change in tendon length which occurs when theone link rotates relative to the other. This joint structure isparticularly useful when two tendons are desired, or when a singletendon loop is desired, where tendon 2230 and 2231 represent outgoingand return portions of a single tendon loop.

FIGS. 23A-23D are diagrammatic illustrations of various convenientforce-transmitting means. FIG. 23A comprises a stationary actuatormodule 2300 and a plurality of rigid straight tendon guides 2305, 2306,2307 and 2308, connected by guiding joints 2302, 2303 and 2304. Each ofthe guiding joints may be a flexible joint (such as in FIGS. 21A and21B), a rigid pinned joint (such as in FIGS. 22A-22E), and the like. Insuch a configuration, the majority of tendon friction losses areassociated with a finite portion of the transmission, namely the jointregions. Rigid portion 2308 may rotate axially relative to rigid portion2307, which is supported by the hand or glove 2301. Tendon 2310terminates at the desired location, which in the case of FIG. 23A is thefingertip 2311.

FIG. 23B is similar to FIG. 23A, however, the actuator module 2312pivots about horizonal axis 2313 and rotates about vertical axis 2314 tominimize the joint flexure of joints 2319 and 2320, which results infriction losses in the tendon. Control signals may come from the fixedportion of the housing 2315 and are transmitted to the actuator module2312 via connection means 2316. Since the actuator module is able toreorient itself depending on the location of the end of theforce-transmitting means, which in this example is the hand, only twojoints 2319 and 2320 are necessary. The joints connect rigid straightportions 2317, 2318, 2322 and 2321. Rigid portion 2322 may rotateaxially relative to rigid portion 2321 via joint 2323. Rigid portion2321 is supported by the hand or glove 2324. The tendon 2325 terminatesin this example at the fingertip 2326.

FIG. 23C is a diagrammatic illustration of how rotational movement froma motor may be transmitted to rotational movement at a terminal point,such as at the hand. In particular, this manner of transmittingrotational movement is useful when used in conjunction with structuressuch as the structure comprising links 2335,2336, 2337, 2338, 2339, and2341 connected by revolute joints. In FIG. 23C, the transmission ofrotational movement is accomplished by a concatenation of tendon loopsand pulleys. In this case, the pulleys rotate co-axially with the axesof the links that separate them. The transmitted rotational movement maybe used in any convenient manner, such as providing a pulling or pushingforce, a rotational torque, and the like. Motor 2327 with pulley 2328drives pulley 2329 via tendon 2330. In this example, the motor isstationed relative to link 2335, about which the entire structure,beginning with link 2336, may rotate about axial joint 2331. Toaccommodate for the resulting change in tendon loop length, rollerpulley 2354 with tensioning spring means 2355 may be used. Typically,other alignment pulleys are also required to prevent the tendon loopfrom coming off the pulleys during rotation; however, they are not shownin the figure for clarity. Pulley 2329 is attached to pulley 2332 whichdrives pulley 2343 via tendon loop 2334. Pulley 2343 is connected topulley 2342 which drives pulley 2343 via tendon loop 2344. Pulley 2343is connected to pulley 2345 which drives pulley 2346 via tendon loop2347. Pulley 2348 transmits force to the desired end location. In thisillustrative example, pulley 2348 imparts abduction/adduction forcesonto the fingertip 2351 of a hand 2350 via tendon 2349; however, any ofa variety of forces or torques may be imparted to the hand or other bodypart. In this example, link 2339 may rotate relative to link 2341 aboutaxial joint 2340. To account for the change in tendon loop length duringrotation, roller pulley 2352 with tensioning spring means 2353 may beused. In practice, other alignment pulleys are used with this axialjoint to ensure that the tendon loop doesn't come off pulleys 2345 and2346. The joints of this structure may have associated joint-anglemeasuring means, such as encoders, flex sensors, and the like, and thejoints may also be actively driven such that the last link 2341 isforcibly drive to a known or desired position relative to the base link2335.

FIG. 23D is a diagrammatic illustration of how a structure similar toFIG. 23C with a set of links connected by revolute joints may beforcibly driven into position, where all actuators are located near thebase link. The grounded-force actuating device of FIG. 23D may be usedto provide grounded forces to a portion of the body, such as the hand,particularly when there is another device associated with the hand whichprovides forces to the hand with respect to another body part, such asprovided in FIG. 1, and the like. When the device of FIG. 23D is used toprovide grounded forces to the hand, it is also a convenient structureby which forces may be transmitted to the hand for use by thehand-referenced force-feedback device, such as provided in FIG. 1, andthe like.

In FIG. 23D, motor 2364 is connected to pulley 2365 which drivesrotation pulley 2367 via tendon loop 2366. By activating motor 2364,link 2358 is caused to rotate about base link 2356 on shaft 2357. Motor2368 is connected to pulley 2369 which drives pulley 2374 via tendonloop 2370, and where pulley 2374 is connected to link 2359 such thatrotation of motor 2368 causes link 2359 to rotate. Motor 2371 isconnected to pulley 2372 which drives idler pulley 2382 via tendon loop2373. Idler pulley 2382 is connected to pulley 2375 which drives pulley2378 via tendon loop 2384, and where pulley 2378 is connected to link2360, such that rotation of motor 2371 causes rotation in link 2360.Motor 2379 is connected to pulley 2380 which drives idler pulley 2376via tendon loop 2381. Idler pulley 2376 is connected to pulley 2383which drives idler pulley 2386 via tendon loop 2385. Idler pulley 2386is connected to pulley 2387 which drives pulley 2389 via tendon loop2388. Pulley 2389 is connected to link 2361 about which the terminallink 2363 may rotate about axial joint 2362. In this figure, terminallink 2363 is affixed to the hand or glove 2377. It is often desirable tohave joint-angle position-sensing means associated with the jointsconnecting the links, such as encoders, potentiometer, flex sensors andthe like. Such joint-angle position-sensing means are not explicitlyshown in FIG. 23D for clarity.

FIG. 24 is a diagrammatic illustration of a pinned joint, such asprovided in FIG. 22A, being used to transmit tendon tension to the hand.Links 2400 and 2401 are connected by axis 2402. Tendon guide sheath 2405is connected rigidly to link 2400, and rotary coupler 2406 is connectedto link 2401. Rotary coupler 2406 rotates about axial joint 2407relative to mating coupler link 2408, which is attached to the glove orhand 2409. Pulley 2403 rotates about axis 2402. Tendon 2404 passesaround pulley 2403, through the rotary-link structure comprising links2406 and 2408, and onto the fingertip 2410 or any other desirableterminal-tendon location.

FIGS. 25A and 25B are diagrammatic illustrations of useful conversion ofthe movement of a circulating tendon loop. In FIG. 25A, a tendon loopcomprising outgoing and return tendon portions 2500 and 2501,respectively, passes around input pulley 2503 which rotates about axis2504 which is held stationary relative to tendon-guide structure 2502.Conveniently, the tendon-guide structure may be attached to a glove orhand with a finger 2508. Input pulley 2503 is connected to output pulley2505 which affects fingertip force applicator 2507 via tendon 2506. Auseful application employs such a structure to impart tension intotendon 2506 which pulls back on fingertip 2507. When tendon 2506 isstiff and appropriately guided, tendon 2506 may also be driven incompression, whereby a pushing force is applied to the fingertip 2507.

FIG. 25B is similar to FIG. 25A, where outgoing- and return-tendonportions 2509 and 2510 pass around input pulley 2512 which rotates aboutaxis 2513 rigidly associated with tendon guide 2511. Input pulley 2512is connected to output pulley 2514 which in FIG. 25B has a tendon loop2515 passing around it. In this illustrative embodiment, two ends of thetendon are connected to the fingertip force applicator 2517 whichcontacts the fingertip. Using this structure, forces to resist or assistfinger flexure may be applied with a non-rigid tendon, i.e., a tendonwhich only transmits tensile forces.

FIG. 26 is an illustrative embodiment, similar in structure to FIGS. 15Cand 14, but where the pulley-support structure is not supported by thehand. Instead, the pulley-support structure may be connected to animmovable object, or to a moving object, such as a force- orposition-programmable robotic arm. The robotic arm may be commanded tofollow the hand such that the fingertips always remain within theworkspace of the hand-linkage system, thus creating an effectivelylarger workspace than is inherent in the hand-linkage system. Oneadvantage to this embodiment is that the user needs to only insert theirfingertips into the device, i.e., they don't need to strap the deviceonto their metacarpus. This makes for quicker donning and doffing,removes reaction forces from non-intuitive portions of the hand, andpromotes better hygiene. In FIG. 15C, the abduction axis shaft 1568,which in FIG. 26 is 2606, with axis 2607, is connected to mountingbracket 2619, rather than the hand backplate. In essence, the“backplate,” may now move independently of the hand, and is shown to bepositioned by a positioning mechanism, shown for example as comprisingthe two links 2620 and 2621. Such a positioning mechanism may be anyrobot-like device, such as a PUMA robot, a SensAble TechnologiesPhantom, and the like.

The remainder of the structure of FIG. 26 operates as follows. Thedevice is a variation on a 5-bar linkage where two of the bars, i.e.,links 2609 and 2608 are position controllable. The position of these twolinks uniquely determines the position of the endpoint 2617 of link2615. The structure was chosen since it permits a wide range of handformations without binding. Tendon portions 2603 and 2602 aretransmitted to the device via tendon guides 2601 and 2600, respectively.These tendons guides may be of any convenient form for transmittingtendon tension, including but not limited to the techniques described inFIGS. 21, 22A-22E, 23A-23D, and the like. The transmitted tendonportions pass around pulley 2604, thus affecting its rotationalposition. Pulley 2604 is rigidly attached to link 2608. Similarly, thereis another tendon-guide structure directly behind the one justdescribed, such that it does not appear in this side-view illustration,but where the associated pulley affects the orientation of link 2609.The three links 2613, 2610 and 1612 are all pinned at their ends, suchthat movement of link 2611 relative to link 2608 causes link 2614 tomove relative to link 2608, hence, moving link 2615. As shown, the endof link 2615 is connected to fingertip force-applying means 2616 whichapplies force, and optionally other sensing signals, to the fingertip2618. The coupling between link 2615 to fingertip force applying means2616 is shown schematically as a pinned joint for simplicity; however,the attachment is typically more complex. The attachment may comprise aball joint, a gimbal, other jointed structure, flexible coupling, andthe like. FIG. 27 provides a diagrammatic illustration of a particularlyuseful gimbal-like structure which may be used for FIG. 26 or any otherappropriate figure. For clarity in FIG. 26, the abduction-controllingmechanism typically associated with shaft 2606 is not shown. Anillustrative example of such an abduction-controlling mechanism isprovided by FIG. 27, where tendon 2721 is guided to the device by guides2720, and passes around pulley 2722, which in FIG. 27 is attached to thebackplate, but is attached to the mounting bracket 2619 in FIG. 26(again, not shown).

As just discussed, FIG. 27 is similar in principle to FIG. 26, with themain difference being the replacement of the variation on the 5-barlinkage with a 7-bar linkage. The 7-bar linkage as shown provides andifferent trajectory for link 2711 (compare with link 2615 in FIG. 26)given angles of links 2706 and 2707 (compare with links 2608 and 2609 inFIG. 26). Obviously, in FIG. 27 the pulley structure is attached to thehand backplate, but it can also be suspended by a fixed or movableobject as was explicitly shown in FIG. 26. In fact, any such figureswith a pulley structure may be interchangeably mounted to the handbackplate or to a fixed or movable structure without departing from thescope of this invention. Similarly, any feedback structures shown for asingle finger may be replicated for multiple fingers.

FIG. 27 does provide a slight perspective view to the point where asecond pulley may be seen. Tendon guides 2700 transmit tendon 2701 froma force generator (not shown). The force generator may comprise anyconvenient force- or position-generating means, such as the motor andspool apparatus provided in FIG. 19. The force generator may alsocomprise a voice coil, a solenoid, nickel-titanium alloy wire (Nitinol),pneumatic motor, hydraulic motor, electric motor, and the like. Thetendon 2701 passes around pulley 2704 which is attached to link 2706.Similarly, tendon guides 2702 transmit tendon 2703 which passes aroundpulley 2705 which is attached to link 2707. The remaining structure isself-evident from the figure, which provides the pinned connections forlinks 2706, 2707, 2708, 2709, 2710 and 2711. The remainder of thestructure implements a gimbal, where link 2711 is connected by axialjoint 2712 to link 2713, which is connected by a revolute joint 2715 tolink 2714, which is connected by an axial joint 2716 to link 2717 whichis rigidly attached to force applicator 2718 which applies forces, andoptionally other sensory stimulations such as texture, temperature,pressure, moisture, and the like to the fingertip 2719. Pulley-supportstructure 2725 pivots about axis 2723 to provide abduction/adductioncapability. Tendon guides 2720 transmit the tendon 2721 which passesaround the pulley 2722 which is attached to the hand backplate, butwhich rotates freely relative to axial joint 2723. By routing tendons tothe hand to rotate the pulleys, rather than placing motors directly onthe hand, or in close proximity to the pulleys, space is conserved andmultiple linkage assemblies may be stacked side by side to accommodatemultiple fingers.

FIG. 28 is a diagrammatic illustration extending the structure of FIG.26 to two hands, and where a force-programmable robot is shown. FIG. 28was drawn to illustrate the concept of a “micro” manipulator providingforce and position control to the hand for subtle hand movements, andwhere a larger “macro” manipulator periodically or continually readjuststhe placement of the micro-manipulator such the user's hand alwaysremains in the usable workspace of the micro-manipulator. As shown, thefingertip force applicators are accessible via inserting one's handsinto openings in a reference structure; however, the entire micro/macroassembly may also reside on a desk top.

For brevity, and since much of the underlying details of FIG. 28 havealready been described or are obvious from the figure, only thedifferences and highlights will be further discussed here. The majorityof the micro-manipulator as shown comprises another variation of a 5-barlinkage (comprising links 2808, 2807, 2806, 2809, 2811, 2812 and 2815,and further comprising joints 2810, 2813 and 2814, and furthercomprising pulley 2805, and further comprising fingertipforce-applicator 2816), which is very similar to the variation describedin FIG. 26, but where “V-shaped” link 2807 replaces the three links2613, 2610 and 2612. The structure of FIG. 28 explicitly provides theabduction-controlling mechanism provided explicitly by FIG. 27. FIG. 28also explicitly provides the fingertip force-controlling gimbal-likemechanism provided by FIG. 27. For clarity, only the terminal portion ofother such feedback structures are shown attached to the thumb fingertipof the right hand and the index fingertip and thumb fingertip of theleft hand. Obviously, the device and concept may be extended to furtherfingertips.

Motor 2801 is attached to a reference structure 2826, where the motorimparts tension to tendon loop 2802, where the tendon loop is guided bytendon guides 2800 which are affixed at one end to guide bracket 2824which is further attached to the reference structure 2826. The other endof the tendon guides is attached to the pulley support structureassociated with the 5-bar linkage assembly, and the tendon loop emergesand passes around pulley 2805. There is obviously anothermotor-tendon-guide assembly which drives the pulley associated with theother link of the 5-bar mechanism.

Motor 2822 is attached to a reference structure 2826, where the motorimparts tension to tendon loop 2823, where the tendon loop is guided bytendon guides 2821 which are affixed at one end to guide bracket 2825which is further attached to the reference structure 2826. The other endof the tendon guides is attached to positioning bracket 2829, and theportion 2828 of the tendon loop that emerges from the guides near thisbracket passes around pulley 2827 which is attached to mounting bracket2820. When motor 2822 rotates its shaft, mounting bracket 2820 is causedto rotate about axial joint 2830 relative to positioning bracket 2829.

The macro-manipulator comprises two motors 2832 and 2837 mounted torotating disk 2839. This disk rotates about axial joint 2844 relative tobase link 2845 attached to a reference location. Motor 2841 has pulley2842 which drives the rotation of disk 2839 via tendon loop 2843. Whenthe disk 2839 rotates, so do both motors 2832 and 2837. These motorsdrive pulleys 2841 and 2835 via tendon loops 2834 and 2840,respectively. Typically, the motors 2832 and 2837 are placed as close tothe axis of joint 2844 as possible to minimize the rotational inertiawhich motor 2841 needs to overcome. Pulley 2835 is connected to link2836, and pulley 2841 is connected to link 2843, which links areattached to link 2831, from which positioning bracket 2829 projects.While the macro-manipulator just described provides one force- andposition-programmable robotic arm, any appropriate robotic-like device,with the desired number of degrees of freedom may be used. The roboticarm as shown provides four degrees of freedom, which is sufficient forsome applications, although other application may require more.

FIG. 29 is a diagrammatic illustration showing a force- andposition-programmable robotic arm which may be used as amacro-manipulator, or as a grounded-force device which attaches to thegrasp-force device of FIG. 1, and the like. Rods 2900 are supported bybearings 2902 which are attached to a shaft 2903 which pivots relativeto shaft supporting members 2904 which are further attached to rotatingdisk 2908. One end of the pair of rods is attached to an end plate 2901.A tendon-guiding spool 2905 rotates freely on the shaft 2903. Anextension tendon 2912 passes from one end plate 2901, around thetendon-guiding spool 2905 and is terminated at its other end at a secondend plate which isn't shown. On the end plate 2901, the tendon 2912 isterminated at a tensioning block 2913. The other end of the rods andtendon, along with the other end plate, have been removed from thedrawing to expose the underlying mechanism. As spool 2905 rotates, itprovides tension to the tendon 2912, causing the rods and end-platestructure to translate relative to the shaft 2903.

The motor 2906 (underneath the plate 2908), has its rotational axisaligned with the rotational axis of the plate. As the spool 2907 whichis connected to the motor shaft rotates, the tendon loop 2911 is causedto move. This tendon 2911 passes around the spool 2907, aroundtendon-guiding-idler pulleys 2909 (which are attached to plate 2908 viasupport structures 2910), and passes around the tendon-guiding spool2905. Thus, as the motor 2906 rotates, the spool 2905 rotates, and sothe rods translate.

The motor 2914 has a pulley 2915. Idler pulley 2916 rotates coaxiallywith the axis of the motor 2906 and plate 2908. Elevation pulley 2919 isattached to the shaft 2903. Elevation tendon 2917 is attached at thenear end of elevation pulley 2919, passes down and around the nearelevation-guide pulley 2918, passes counterclockwise around idler pulley2916, passes clockwise around motor pulley 2915, continues on to passaround the idler pulley 2916 again, passes under the far elevation-guidepulley 2918, up the far side of the elevation pulley 2919, and iffinally anchored at the top of the far side of the elevation pulley2919. Thus, when the motor 2914 rotates, the elevation pulley rotates,and the rods change their angle of elevation.

The motor 2920 has a pulley 2921 which drives the plate 2908 to turn viatendon 2922. Thus, when motor 2920 turns, the rods also turn about theaxis aligned with the axis of motor 2906. Note that various supportdetails for the plate 2908 have also been eliminated from the figure forclarity. One advantage of this design is that is requires no translationof any of the motors, thus inertia is minimized. Various modification tothe design may be conveniently made, such as the rods may be one overthe other. Various rod cross sections may be employed, includingtriangular and rectangular. Various bearing constructions may be used,such as roller wheels, each position at 120 degrees orientation relativeto the other, with the rod passing through the projected vertex of theroller wheels.

FIG. 30 is a diagrammatic illustration of a hand-feedback device 3003,such as provide by FIG. 1, and the like, being attached at the fingertip3001 to a force- or position-programmable robot arm 3000 by a coupler3002. Such an arm may be any appropriate robotic-like arm, such as aPUMA arm, a Phantom arm by SensAble Technologies, and the like. The handfeedback device may comprise any type of feedback, for example graspforces which are local to the hand, such as is provided by the device ofFIG. 1. The hand-feedback device may also comprise tactile elements, forinstance on or more vibratory elements 3004, such as are provided by theCyberTouch product manufactured by Virtual Technologies, Inc. In thecase of vibratory feedback, the robotic arm would provide theground-referenced force to one or more fingers, while thetactile-feedback elements provided tactile feedback to the same or otherfingers. By using the robotic arm along with the hand-referencedgrasp-force-feedback device of FIG. 1, again, ground-referenced forcescan be applied to one or more fingers, while forces on the fingersrelative to the hand can be applied to the same or other fingers. Therobotic-like device may be attached to any portion of the hand toprovide ground-referenced forces and positioning. The location ofattachment to the hand affects the sensory perception. The robotic-likedevice may also provide absolute location information for the hand.

FIG. 31 is a diagrammatic illustration of a fingertip of a hand beingpositioned by a robotic-arm-like device 3100, connected to theforce-applying device 3101 via a coupler 3102. Here it is assumed thatthe position of the point of attachement of the robot arm to the hand isknown from the robot arm. Associated with the hand is an alternateposition-sensing device, such as an electromagnetic 6-DOF-positioningdevice 3101 manufactured by Polhemus, Inc. or Ascension Technology Corp,both located in Vermont. As shown, the position-sensing device 3103 issupported on the hand by support 3106. If the hand is modeled as a setof links 3104 interconnected by constant-axis revolute joints 3105, thenby using the position of the fingertip from the robot arm, and theposition of the metacarpus from the 6-DOF position-sensing device, andusing an inverse kinematic mathematical determination as described inU.S. Pat. No. 5,676,157, the joint angles 3105 can be determined. Oncethese joint angles are determined, using forward kinematics, a graphicalhand can be displayed on a computer screen which mimics the movements ofthe hand and finger.

FIGS. 32A and 32B are diagrammatic illustrations of a movement-impedingapparatus. The figures show such an apparatus in combination with aportion of the grasp-force-feedback device 3200 such as is provided inFIG. 1, and the like. As shown in FIG. 32A, when the finger is flexed,tendon 3201 slides relative to guide 3202 which is typically attached toa glove or hand. As shown in FIG. 32B, to impede movement of the finger,actuator 3203 is activated, withdrawing rod 3204 and element 3205, suchthat guide 3206 collapses onto the tendon 3201, opposing its movementrelative to the guide, or even preventing it from further movingrelative to the guide altogether. Actuator 3203 may be any convenientactuator such as a solenoid, voice coil, motor, and the like. If tendon3201 is stiff, actuation of actuator 3203 can also prevent the fingerfrom extending. In general, the entire actuator may be replaced with amore conventional brake- or clutch-like mechanism which impedes orprevents movement.

FIGS. 33A-33D are diagrammatic illustrations a canonical force-feedbacksystem, representing any of the force-feedback embodiments described inthe subject application, being used with a 3D display system. FIG. 33Ashows the canonical force-feedback system 3300 being used with a displaysystem employing a computer monitor 3303 projecting onto a parabolicmirror 3302. Due to the optical effects of the parabolic mirror, avirtual image 3301 of what is displayed on the monitor will appear in 3Dat the focal point of the mirror. Thus, without any further viewingrequirements, the user perceives that they are manipulating the virtualobject with their hand which is wearing the canonical force-feedbackequipment.

FIG. 33B is a diagrammatic illustration of a canonical force-feedbacksystem 3304 attached to a glove 3320 which is further attached to theopening 3306 in a viewing structure 3308. The glove has enough structurethat it maintains its form, even without the presence of a hand in it.Such a glove can be made from rubber, plastic, neoprene, and the like.Although a variety of viewing systems may be used, the one discussedhere 3305 comprises one or more computer monitors or TVs, withappropriate optics in front to give, the perception that the objectdisplayed on the screen is behind the display. Such display technologyis common place for head-mounted displays known to those skilled in theart of virtual reality. The display gives the viewer the perception thatthe object they see is real and resides within the viewing structure3308. Associated with the glove 3320 are sensors such that theconfiguration of the hand is known by a computer (not shown). Thecomputer displays for the user a graphical representation of their hand3307, along with the object 3309, and performs collision and forcecalculations between the hand and object, and displays the forces on thehand by the canonical force-feedback system. Such a viewing-feedbacksystem finds utility in museums and the like where people need toquickly insert and remove their hands from the device.

FIG. 33C is a diagrammatic illustration of a canonical force-feedbacksystem 3321 being used below a mirror 3311 where the user inserts theirhand under the mirror at location 3319. A computer monitor 3312supported by support structure 3314 projects an image onto the mirrorwhich reflects to the eyes of the user. The monitor may alternatedisplaying views slightly offset to the left and right (corresponding tothe different images seen by one's eyes) of images of the virtual hand(calculated as before using measurements of the physical hand) andvirtual object 3322, then by synchronizing LCD glasses 3313 with thealternating left-right-shifted views, the viewer receives a 3Dstereoscopic perception. Such LCD glasses viewing technology is providedby Crystal Eyes®. Thus the viewer perceives that they are manipulating areal object beneath a pane of glass.

FIG. 33D is similar in concept to FIG. 33C, however, the monitor-mirrorcombination is replaced by a flat-panel display 3315 atop supportstructure 3316. Again, left-right-eye views are alternated andsynchronized with LCD glasses 3317, giving the viewer a stereoscopicperspective that there is a real object under 3318 the counter top whichthey are manipulating. A computer (not shown) calculates the views andforces associated with the canonical force-feedback device and thevirtual object.

FIG. 34 is a diagrammatic illustration of a simulation chair 3407. Thechair finds use in entertainment, military training, flight and drivingdraining, and the like. The chair may include any of our force-feedbackdevices described in the subject application. In addition, the chair mayincorporate a head-mounted display 3427, motion platform 3421,steering/moving pedals 3412 and 3413, headphones 3428, microphone 3434,vibration-inducing speakers 3411, a control unit 3430, a computer 3432,interconnects 3431, 3429 and 3435, a network connection 3433, and thelike. As shown to exemplify the concept, a micro/macro feedback device3402 similar to that provided in FIG. 28 is attached to the left side ofthe chair. The macro part of the feedback device comprises pulleys 3405,3406 and 3404 to provide elevation, extension and rotation of the micropart. For clarity, details of the attachment means and actuation meansfor the macro-manipulator are not shown. To the end of themacro-manipulator is attached a micro-manipulator 3400 driven by motors3410, and others which are not shown. Again, to exemplify the concept, agrasp-force-feedback device 3408 similar to that provided by FIG. 1, andthe like, is shown connected to the right side of the chair seat. Anyappropriated feedback device may be used with either hand. Othernavigational aids such as a joystick, SpaceBall®, trackball, and thelike may also be positioned near the chair. The steering pedals 3412 and3413 are connected to legs 3418 and 3419. Angle measuring means 3414 and3417, such as encoders, flex sensors and the like determine pedalangles. The pedals 3412 and 3413 also may have return springs 3416 and3415 to keep the pedals extending up. The motion base may be anysuitable technique for modifying the position and orientation of thechair. To exemplify the concept, a motion platform with threecontrollable elevating motors 3420 is shown. By appropriately energizingone or more of the motors, a variety of tilts can be effected. Themotors may be any appropriate actuator, including electrical motors,pneumatic motors, hydraulic motors, voice coils, solenoids and the like.A motor 3424 is used to rotate the chair relative to the motion base.The motor has a pulley 3425 which is connected via tendon loop 3426 tochair pulley 3423 which turns chair post 3422 to which the chair cushion3407 is attached.

FIG. 35 is a diagrammatic illustration of a variant on the simulationchair of FIG. 34. In FIG. 35, the chair 3502 again comprises any of thefeedback devices described in the subject application, where for purposeof example, the grasp-force feedback device of FIG. 13500 is shown withactuator module 3501 mounted to the side of the chair. The chair of FIG.35 may contain any of the components and features of the chair of FIG.34; however, the method of navigation is different. Rather than thesteering/forward pedals 3412 and 3417 of FIG. 34, a “barstool” bar 3505is employed to control forward movement. The chair 3502 is able torotate about the axial joint 3503 relative to the base 3504. Typicallythe rotation is effected by human power, i.e., pushing the chair withone's feet until the desired direction is determined. Once the directionis determined, the farther down the bar 3505 is pressed, the faster onemoves in that direction.

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication or patent application was specificallyand individually indicated to be incorporated by reference.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best use the inventionand various embodiments with various modifications as are suited to theparticular use contemplated. It is intended that the scope of theinvention be defined by the Claims appended hereto and theirequivalents.

What is claimed is:
 1. A robotic force-feedback system, said systemcomprising: a force-feedback device for contacting a human hand having asensing link connected to a non-sensing link with at least one sensingjoint between the sensing and non-sensing links, said device comprisinga force applicator adapted to apply a force to the sensing link; forceapplication means for applying a generated force between said sensinglink and said non-sensing link, said force application means comprisinga moment-augmenting structure, a tendon elevated by saidmoment-augmenting structure, said tendon connected to said forceapplicator and capable of transmitting the generated force to the forceapplicator; a manipulator disposed at a location separated from saidforce-feedback device; and a communication link between saidforce-feedback device and said manipulator.
 2. An interactive computersystem comprising: first and second force-feedback interface devices forright and left hands of a human operator, each said interface deviceincluding means for sensing the force applied to at least one fingertipof a finger and generating a sensed applied force signal related to saidsensed force, and means for controlling the fingertip force in responseto said sensed applied force signal, wherein said fingertip force mayvary as a function of finger position; a display device for presenting agraphic environment to said human operator; and simulation meansreceiving said sensed signals and information about said graphicenvironment and communicating feedback to said human operator as saidhuman operator interacts with said graphic environment.
 3. A roboticforce-feedback system according to claim 1 wherein said device comprisesa glove.
 4. A force-feedback system according to claim 1 wherein theforce applicator comprises a platform and wherein the platform may bemoved from a first position displaced from the sensing link to a secondposition in contact with the sensing link.
 5. An interactive computersystem according to claim 2 wherein the computer system is a computeraided design system and wherein said graphic environment is a designenvironment.
 6. A force-feedback system comprising: a device adapted tocontact a human hand having a sensing link connected to a second linkwith at least one joint between the sensing link and the second link,the force-feedback device comprising a force applicator adapted to applya force to the sensing link; and force application means for applying agenerated force to the sensing link, said force application meanscomprising a moment-augmenting structure positionable on the human hand,a tendon elevated by said moment-augmenting structure, said tendonconnected to said force applicator and capable of transmitting thegenerated force to the force applicator.
 7. A force-feedback systemaccording to claim 6 wherein the force application means applies a forcebetween the sensing link and the second link.
 8. A force-feedback systemaccording to claim 7 wherein the second link is a non-sensing link.
 9. Aforce-feedback system according to claim 6 wherein the joint is asensing joint.
 10. A force-feedback system according to claim 6 furthercomprising a force generator remote from the force applicator.
 11. Aforce-feedback system according to claim 6 wherein the tendon isenclosed along at least a portion of its length by a casing.
 12. Aforce-feedback system according to claim 6 wherein the force applicatorcomprises a force sensor capable of generating a signal related to theforce applied to the sensing link.
 13. A force-feedback system accordingto claim 12 further comprising a control system for controlling thegenerated force is response to the signal.
 14. A force-feedback systemaccording to claim 6 wherein the moment-augmenting structure comprisesfirst and second elements connected by an articulation.
 15. Aforce-feedback system according to claim 14 wherein the first and secondelements move in the same plane.
 16. A force-feedback system accordingto claim 6 wherein the moment-augmenting structure comprises aflexure-articulating component and an abduction articulating component.17. A force-feedback system according to claim 16 wherein themoment-augmenting structure further comprises two revolute joints.
 18. Aforce-feedback system according to claim 6 wherein the moment-augmentingstructure comprises a member comprising means for attachment to anintermediate link between the sensing link and the second link.
 19. Aforce-feedback system according to claim 6 wherein the force applicatorcomprises a platform.
 20. A force feedback system according to claim 19wherein the platform may be moved from a first position displaced fromthe sensing link to a second position in contact with the sensing link.